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Reduce friction:How, Why,When,Examples And Exhaustive Facts

January 21, 2024December 6, 2021 by Prajakta Gharat

Reduce friction simply means the lowering the resistance of the body. There are many different types of approaches and methods to reduce friction. Let us see those methods in details.

By grinding the surfaces to a smooth finish.
By making use of lubricants
By streamlining the body
By using electrostatic magnetic levitation to reduce contact between surfaces
By using sliding friction instead of rolling friction
By using fluid friction instead of dry friction
By reducing the amount of pressure or weight applied on the body
Frequently Asked Questions (FAQ’s)

First let us get some basic idea about the reduce friction.

Reduce friction:

The term “reduce friction” simply refers to “minimise the friction.”

A surface or an object experiencing friction is defined as the resistance they encounter as they are moved over another. This resistance created by the friction causes wear and tear between the surface which are in contact and hence it is necessary to reduce friction.

Now let us see various methods mentioned below of reduce friction in details along with its examples.

Different approaches and methods to reduce friction and their examples

1.By grinding the surfaces to a smooth finish.

Friction is created when two surfaces slide over one other. In terms of friction, the sticking mechanism at the microscopic size is the most important component to consider. Making the sliding surfaces smoother will help to lessen the amount of sticking.

There are three types of methods to smooth the surfaces

Grinding
Using sand papers
Chemical itching

Examples

Polishing the wooden furniture and sculpture
Removing corrosion with the help of chemicals

2.By making use of lubricants

Lubricants are chemicals that are applied to surfaces with the goal of reducing friction. It has the potential to minimise heat generation while also ensuring smooth sliding. Lubricants are usually semi-solid paste-like compounds that are used to minimise dry sliding friction by reducing frictional heat generation.

Examples

Lubricants in the engine components of an automobile.
The use of protective paints to keep metal from oxidising
Oiling the door hinges will make them easier to open and close.
Grease is used to keep bicycle parts moving smoothly.

Reduce friction — **Lubricants such as oil**

Image Credits: Image by Dibyendu Joardar from Pixabay

3.By streamlining the body

A streamlined body aids in the reduction of friction, which is especially important in fluids. It makes it possible for the sliding body to travel through the medium with the least amount of resistance.

Examples

The streamlined bodies of fish and birds are copied in order to guarantee that there is as little friction as possible.

4. By using electrostatic magnetic levitation to reduce contact between surfaces

Friction can be reduced by reducing the amount of contact made during sliding. Through the use of magnetic levitation or charging both surfaces with the same polarity, we may significantly decrease touching.

Examples

A maglev train operates on the idea of magnetic levitation, which reduces friction and allows for faster travel while also providing a more comfortable ride for passengers.

Image Credits: Lars Plougmann, The Shanghai Transrapid maglev train, CC BY-SA 2.0

5.By using sliding friction instead of rolling friction

Sliding friction is always larger than rolling friction, regardless of the situation. Consider the possibility of an automobile with square wheels. Friction created by rolling is used extensively in our daily lives.

Examples

Ball bearings are used to separate two bearing races by using balls as separators between the two races. The result is that sliding friction becomes rolling friction. The races will no longer glide over one another, but will instead pass the weight to the balls through rolling friction instead.
Vehicle breaking mechanism
Rubbing our own hands together

6.By using fluid friction instead of dry friction

When compared to solid surfaces, fluids have lower coefficients of friction. Because they are very resistive to motion, fluids having a high density have a high coefficient of fluid friction. As a result, aeroplanes can move at far higher speeds than automobiles. In addition, when we apply lubricants or oil to surfaces, we are effectively changing dry friction into fluid friction, which is beneficial.

Examples

Diving into the water
Walking on an oily surface
Swimming of the fishes in water

7. By reducing the amount of pressure or weight applied on the body

The amount of friction created is exactly proportional to the amount of normal force that is applied to the friction surface. The weight of the body acts as a normal force on the object due to the fact that we are on the surface of the planet. There will be very little or no friction in space. Selecting the right materials to decrease friction is so important.

Frequently Asked Questions (FAQ’s):

Q. What is reducing the friction?

Ans: Reduce friction simply means reducing resistance.

Smoothening of the surfaces which are in contact with each other to make them function easy and to avoid the production of frictional heat, is called the reduce friction.

Q. Why do we reduce friction

Ans: In some cases, it is necessary to make system work smoothly.

A necessary part friction is responsible for most of the wear and tear on working parts. Destroying the uniformity of the surfaces is one of its primary effects. Because of this, it is suggested that friction be reduced in specific circumstances.

Q. When would you want to decrease friction

Ans: It is sometimes essential to minimise friction in order to ensure safety from occurring.

The term “opposing force” refers to the fact that friction always acts in the opposite direction of a body that is moving or attempting to move. We aim at reducing friction where it is unnecessary. When machine parts are in contact with each other, friction reduces the efficiency of the machine; consequently, we oil them to minimise friction. Oil separates surfaces, which reduces friction between them.

Q. Reduce friction examples

Ans: Following is the list of examples of reduce friction

Walking on the ground
Cycling on the road
Vehicles braking system
Sanding
Train wheels
Trolley bag wheels
Roller skating
Lubricants in the hinges
Flying bird
Oiling the engines
Powder on carrom board

Q. Why do we increase or reduce the friction

Ans: Friction is the vital thing in our daily life and surrounding.

A firmer grasp on the object is required in order to maintain control over its motions. For example, if there is no friction on the road, the car would slip and will never come to a complete stop; thus, roads are constructed using concrete to enhance the amount of friction. However, it is generally important to lessen the friction in order to ensure that the machines operate as smoothly as possible. Consequently, depending on the requirements of the system under consideration, it is necessary to either enhance or decrease friction.

Q. Can we reduce friction to zero

Ans: We will never be able to entirely remove friction since it is required for any motion.

Without friction, we would be unable to picture any motion because there is no motion on a smooth surface. A substantial quantity of lubricants, such as oil, water, and grease, can be used to minimise friction to a great extent but it is not possible to completely eliminate friction.

Q. Does sand reduce friction

Ans: As the concentration of sand particles in the lubricated sliding contact rises, the friction and wear rates in the sliding contact increase proportionally.

Q. Does lubricant increase or decrease friction

Ans: Regular lubrication with oil or grease is required to decrease friction between machine components.

Lubrication reduces the amount of heat generated when two moving surfaces come into contact. Because it forms a film between two surfaces, it makes the process smoother and more efficient by reducing friction and so improving performance and efficiency.

Q. How do lubricants reduce friction

Ans: The term “lubricant” can be described as a material, such as grease, that when applied as a layer between two solid surfaces, reduces friction, heat generation, and wear and tear.

Lubricants are often organic in nature, and it is added to minimise friction between surfaces that are in mutual contact, which in turn lessens the amount of heat created when the surfaces move. Lubricants can also perform other functions such as conveying foreign particles, transferring forces, and heating or cooling the surfaces they come into contact with, among others.

Q. Does water reduce friction

Ans: Water is typically effective in reducing friction between two surfaces. In order to reduce friction between two surfaces, water must act as a barrier between the two surfaces. It does this by separating them and reducing the contact area between them. It can only accomplish this if none of the surfaces is absorptive; otherwise, the water will not be able to stay between the two surfaces.

Q. How will you decrease friction on your floors

Ans: The simpler way to decrease or reduce friction on your floors is by polishing the surface of the floors. By polishing the surface of the floor, roughness gets decreased and resulting into smooth surface.

Q. Does graphite reduce friction

Ans: Friction is reduced to an extreme degree by the lamellar structure of graphite. To prevent direct contact between the metals and the development of adhesion and scuffing during the friction process, solid graphite lubricant can be applied over the surface of the counterpart.

Q. Do ball bearings reduce friction

Ans: Ball bearing is the best example of rolling friction.

Whenever the axle rotates, the steel balls and wheel revolve in the opposite direction of the axle’s rotation. As a result, the rolling friction between the two cylinders is lower than the sliding friction between them. Bearings that roll rather than slide minimise friction as a result of the rolling friction that they generate.

Sliding friction is turned into rolling friction as a result of the usage of rollers and wheels in production. Because rolling friction is less than sliding friction, we may lower the amount of force necessary to move an item by using rollers and wheels. As a result, the object can be moved more readily when using rollers and wheels.

Q. Is there friction in the desert

Ans: It is difficult to walk on the desert sand.

Our feet and sand particles have less friction when we step on sand. While walking on the sand, our feet become slippery due to the rolling. As a result, walking on sand is more difficult due to the reduced friction.

Q. Does powder reduce friction

Ans: Sliding friction is the friction come into play when we use powder on any surface.

When talcum powder is dry, it has a minor friction-reducing effect on some materials against the skin, but when it is wet, it has the opposite effect. Additionally, powder is highly suggested and should be placed on the surface of the carrom board to smooth up the surface. Due to this striker and other coins of the game can easily slide.

Q. Does ice reduce friction

Ans: Sliding on ice or snow is significantly less difficult than sliding on most other surfaces, and no one denies that fact. However, although liquid water at the ice surface reduces sliding friction on ice, the current opinion is that this liquid water is not dissolved by pressure, but rather by the frictional heat created during sliding.

Q. Does rain increase friction

Ans: When water is present in sufficient quantities, it works as a lubricant. The quantity of rain that falls and the amount of standing water on the pavement can both have an impact on this change in elevation. Heavy rains may frequently reduce the coefficient of friction to 0.4, which is about half of what it would be on a dry pavement under normal conditions.

Q. Does tire tread reduce friction

Ans: Tire tread is meant to channel water away from the wheel when roadways are moist.

In rainy weather, when the roads are slick from rain or snow, tyre tread is designed to channel extra water away from underneath the wheel. This enables for the greatest amount of contact between the road and your tyre when it is most needed. To minimise dangerous slippage on snow and ice, winter tyres are even designed to have more gaps in the treads than regular tyres.

Q. Does car brakes reduce friction

Ans: Most of the car brakes employ friction between two surfaces to convert kinetic energy into heat.

Car brakes operate because of friction; the brake pads push down on the rotors, which causes the friction to slow the wheels. Friction is what causes brakes to work. Because it determines how much power is used to drive the rotors and pads together, the brake pedal has the ability to alter the degree of friction.

Q. How do air cushions reduce friction

Ans: An air cushion may be created on any flat surface, whether it is on land or in water, by trapped air currents! It is possible to glide effortlessly over the smooth surface underneath because of the cushion’s significant reduction in frictional resistance.

Q. How does water affect the friction of sand

Ans: The addition of a little amount of water but not too much to sand significantly reduces sliding friction.

Small quantities of water can generate capillary bridges, according to most experts. The shear modulus of the sand is increased by the creation of capillary water bridges, which makes sliding easier. When the capillary bridges become clogged with too much water, the modulus decreases, causing the friction coefficient to rise once again.

Q. Does chalk powder reduce friction

Ans: Magnesium carbonate, sometimes known as ‘chalk,’ is a substance that is used to improve the coefficient of friction.

The particles in talcum powder are tiny, but the particles in chalk powder are large. Friction is mostly caused by differences in surface area. Because talcum powder has a smaller surface area than chalk powder, it decreases friction, whereas chalk powder has a higher surface area and increases friction. There is less friction on a smaller surface area, hence it produces less friction.

Q. How does a hovercraft reduce friction

Ans: Slow-moving, low-pressure air vents or currents are ejected downward against the surface of the water below the hovercraft. It is possible to glide effortlessly over the flat surface underneath because of the cushion’s significant reduction in friction.

Q. How does oil reduce friction

Ans: Oil is introduced to the engine in order to minimise friction.

A thin coating of oil is created between the two surfaces when oil is placed between them. The oil coats the moving components’ surfaces, making them slippery as a result of the friction. When they brush against one other, the interlocking between the two surfaces is much decreased because of this layer. It is easier for them to slide over one another, resulting in less friction.

Q. How do you reduce friction in big machinery and cars

Ans: The use of lubricants such as oil and grease, as well as the use of ball bearings between machine elements, can help to reduce friction. A lubricant is a substance that is placed between two surfaces that are in touch with the goal of minimising friction between them.

Q. How to reduce friction between wood

Ans: The friction between the woods can be reduced by polishing the surfaces using the sand papers. Also, special lubricant called as varnish can lower the friction coefficient of several materials. The high static friction coefficient of these elastomers is a common characteristic. Coating with lubricating varnish can effectively reduce the stick-slip effect in actual use.

Q. Reduce friction between two surfaces

Ans: There are many ways to reduce friction between the surfaces in contact.

Polishing the surface helps minimise friction by smoothing out the surface. It is possible to minimise friction by using lubricants such as oil or grease, which may be applied to the surfaces. Ball bearings can be used to lessen the friction between a rolled object and the surface it is rolling on.

Q. What is the effect of reducing friction on a machine

Ans: Increasing the efficiency of a machine while simultaneously minimising the amount of hazardous heat generated between machine elements is the result of reducing friction on the machine. The excessive creation of heat will harm machine parts if friction is not reduced. Furthermore, if the friction isn’t decreased, the process will demand more power.

Also Read:

How To Find Coefficient Of Kinetic Friction (Updated 2023)

January 21, 2024November 30, 2021 by Keerthi Murthi

A dimensionless physical quantity the specifies the interaction of two object is called coefficients.

The value coefficient of kinetic friction is changes depending on the nature of the material used. Generally, the coefficients give the ratio of two quantities involved in the action. In this post, let us discuss how to find coefficient kinetic friction and its consequences.

How to find coefficient of kinetic friction

Let us consider two surfaces, such that one surface is moving in contact with another one. The friction always resists the movement and finally stops the motion of the surface in the opposite direction of the motion.

A general formula to find the coefficient friction is given by the ratio of friction force and the normal reaction acting on the surfaces in a perpendicular direction.

Image credits: Image by Pexels from Pixabay

how to find coefficient of kinetic friction — **Free body diagram of Kinetic Frictional Force**

On rearranging the above expression, we can find out the kinetic friction as well.

How to calculate uncertainty of coefficient of kinetic friction

The uncertainty occurs due to the misalignment of the coordinate axes along the direction of the motion. Along with the normal force, the tangential force is acting on the system. This tangential force gives an account for the occurrence of uncertainty of the coefficient of the kinetic friction.

The value of the coefficient is not measured directly through the experiment. It is determined by calculating all the forces acting on the system and the angle of inclination of the object with the surface.

The general expression for the coefficient of kinetic friction is given by

Let us consider the sliding of an object in a plane. The sliding of the object is taken for the various angle of the object along the plane for different instances. Then calculate the coefficient of kinetic friction for all the angles.

The above statement tells that the value of coefficient of kinetic friction changes with change in the angle. This deviation is due to the uncertainty of kinetic friction coefficient. Let us study how to find the coefficient of kinetic friction with uncertainty.

Along with the normal force F_N, the tangential force also contributes to the evolution of friction force. This leads to an error in calculating the coefficient of kinetic friction. The uncertainty measurement compensates for the error that occurred during the calculation.

The normal force is acting along the Y-axis, and the angle of misalignment be β. And the tangential force is acting along the X-axis with the misaligned angle of α. These normal and tangential forces are in contact, and the resultant force along the X and Y axes are given by

F_X = F_F cosα + F_N sinα

F_X = µ_K F_N cosα + F_N sinα

F_X= F_N (µ_K cosα + sinα)

Similarly for Y axis

F_Y = F_N cosβ – F_F sin β

F_Y = F_N (cosβ – µ_K sinβ) By solving the resultant forces, the uncertainty in the friction is given as

In order to calculate the combined standard uncertainty measurement, the standard uncertainty function must be a standard value of input values and the partial derivatives of the frictional coefficient. The law of “propagation of uncertainty” helps us to give a standard value for the uncertainty in the friction. It is given by the equation.

Where, u is the uncertainty of the given system.

On differentiating the individual variables, we get the standard value of uncertainty in the coefficient of kinetic friction.

This gives the standard uncertainty value for the input forces acting on the system. By substituting these values in the partial derivative equation, we get the uncertainty value.

How to calculate coefficient of kinetic friction without mass

To calculate the coefficient of kinetic friction without mass, let us consider a block moving on a flat surface. The block of mass “m” moving with acceleration “a” in the direction of the applied force. The normal force acting between the block and the surface be F_Nwhich is perpendicular to the motion of the block. We know that the friction force acting between the block and surface to retard the motion is given by the equation,

F_K = µ_K F_N

According to Newton’s second law of motion, the force acting on the moving body equals mass times the acceleration.

F = m* a

The normal force is influenced by the force of gravity given as

F_N= m*g

Substituting in the equation of frictional force, we get

F_K = µ_K m*g

Since the body is moving and the force acting on the block is kinetic friction force, Newton’s law can be modified as

F_K = m* a

On equating the above two equations we get,

µ_K m*g = m* a

µ_K g = a Rearranging the equation we get,

This gives the value of the coefficient of kinetic friction.

Determining the Coefficient of Kinetic Friction on an Inclined Plane

Kinetic Friction on an Inclined Plane

Forces Acting on the Object:

Gravitational force: $F_{gravity} = m cdot g$
Normal force: $F_{normal}$
Frictional force: $F_{friction}$

Decomposing the Gravitational Force: The gravitational force can be split into two components:

Parallel to the incline: $F_{gparallel} = m cdot g cdot sin(theta)$
Perpendicular to the incline: $F_{gperp} = m cdot g cdot cos(theta)$

Frictional Force: When an object moves at a constant velocity on the incline:

Since $F_{normal} = F_{gperp}$ , and $F_{friction} = F_{gparallel}$ , we get: $mu_k = tan(theta)$

Example:

Suppose you have a block on a 30° incline, and you notice it starts to slide at a constant velocity without any external push. Determine the coefficient of kinetic friction.

Given: $theta = 30^circ$

To find: $mu_k$

Using the formula: $mu_k = tan(theta)$

Plugging in the given value: $mu_k = tan(30^circ)$ $mu_k approx 0.577$

Thus, the coefficient of kinetic friction between the block and the incline is approximately 0.577.

How to Find the Coefficient of Kinetic Friction with Acceleration

Kinetic Friction with Acceleration

When an object slides over a surface, it experiences a resistive force due to the surface. This resistive force is called kinetic friction. The magnitude of the kinetic frictional force ( $F k $ ) is given by:

$F_{k} = mu_{k} times N$

Where:

$mu_{k}$ is the coefficient of kinetic friction.
$N$ is the normal force (or the force acting perpendicular to the surface). In many cases, this is equal to the weight of the object if the surface is horizontal.

If an object is moving on a horizontal surface and no other horizontal forces are acting on it, then the net force ( $F_{net}$ ) acting on the object due to friction is:

$F_{net} = F_{k}$

Using Newton’s second law ( $F_{net} = m times a$ ), where $m$ is the mass of the object and $a$ is its acceleration, we can equate the above equations to find:

$m times a = mu_{k} times N$

To solve for $mu_{k}$ , you can rearrange this equation:

$mu_{k} = frac{m times a}{N}$

Example:

Suppose we have a block of mass 10 kg sliding on a horizontal surface. The block has an acceleration of 2 m/s² in the direction of motion. Given that the gravitational acceleration ( $g$ ) is approximately 9.81 m/s², we want to find $mu_{k}$ .

First, calculate the normal force ( $N$ ):

$N = m times g$ $N = 10 text{ kg} times 9.81 text{ m/s}^2 = 98.1 text{ N}$

Then, use the formula for $mu_{k}$ :

$mu_{k} = frac{m times a}{N}$ $mu_{k} = frac{10 text{ kg} times 2 text{ m/s}^2}{98.1 text{ N}}$ $mu_{k} approx 0.204$

So, the coefficient of kinetic friction between the block and the surface is approximately 0.204.

How to Find the Coefficient of Kinetic Friction Without Friction Force

kinetic friction without friction force

In real-world scenarios, you may not always have a direct measure of the frictional force between two surfaces, but there might still be a need to determine the coefficient of kinetic friction ( $μ k $ ). One way to derive $μ k $ is by analyzing the motion of an object on an incline.

When an object is sliding down an incline without acceleration (i.e., at constant velocity), the net force acting on it is zero. This means that the component of gravity pulling it down the incline is balanced by the frictional force resisting its motion.

Let’s dive into the mathematics of this:

Gravitational Force Parallel to the Incline

The component of gravitational force acting parallel to the incline can be found using:

$F_{parallel} = mg sin(theta)$

Where:

$m$ is the mass of the object.
$g$ is the acceleration due to gravity (approximately $9.81 , text{m/s}^2$ near the Earth’s surface).
$theta$ is the angle of inclination.

Frictional Force

The frictional force acting on the object can be represented as:

$F_{friction} = mu_k N$

Where $N$ is the normal (perpendicular) force. For an incline, the normal force is given by:

$N = mg cos(theta)$

Thus, the frictional force is:

$F_{friction} = mu_k mg cos(theta)$

Balancing the Forces

At constant velocity:

$F_{parallel} = F_{friction}$

Substituting in our expressions:

$mg sin(theta) = mu_k mg cos(theta)$

From this, we can solve for $mu_k$ :

$mu_k = tan(theta)$

Worked-out Example

Let’s say an object is observed to slide down an incline at a constant velocity, and the angle of the incline, $theta$ , is measured to be 30°.

Using the derived formula:

$mu_k = tan(30^{circ})$

$mu_k approx 0.577$ (rounded to three decimal places)

Thus, the coefficient of kinetic friction, $mu_k$ , between the object and the incline is approximately 0.577.

NOTE: this method assumes no other forces (like air resistance) are acting on the object, and that the object moves at a constant velocity down the incline.

How to Find the Coefficient of Kinetic Friction Using Velocity and Distance

In many experimental or real-world scenarios, you might have information about the initial velocity of an object and the distance it traveled before coming to a stop due to friction. This data can be invaluable in determining the coefficient of kinetic friction ( $μ k $ ) between the object and the surface it’s sliding upon.

kinetic friction with velocity and distance

Let’s understand the principles behind this:

Work Done by Frictional Force

The work done by the frictional force over the distance ( $d$ ) is equal to the change in kinetic energy of the object.

$W_{friction} = mu_k N d$

Where:

$N$ is the normal (perpendicular) force. On a horizontal surface, $N = mg$ , where $m$ is the mass of the object and $g$ is the acceleration due to gravity (approximately $9.81 , text{m/s}^2$ ).

Change in Kinetic Energy

The object’s initial kinetic energy (when it has velocity $v$ ) is:

$KE_{initial} = frac{1}{2} mv^2$

Since the object comes to a stop, its final kinetic energy is zero. Thus, the change in kinetic energy is:

$Delta KE = frac{1}{2} mv^2$

Equating Work and Change in Kinetic Energy

For the object to come to a stop:

$W_{friction} = Delta KE$

Substituting in our expressions:

$mu_k mgd = frac{1}{2} mv^2$

From this equation, we can solve for $mu_k$ :

$mu_k = frac{v^2}{2gd}$

Worked-out Example

Imagine an object sliding on a horizontal surface. It has an initial velocity of $5 , text{m/s}$ and comes to a stop after traveling $10 , text{m}$ . Let’s determine the coefficient of kinetic friction, $mu_k$ , between the object and the surface.

Using the derived formula:

$mu_k = frac{5^2}{2(9.81)(10)}$

$mu_k approx frac{25}{196.2}$

$mu_k approx 0.127$ (rounded to three decimal places)

Thus, the coefficient of kinetic friction, $mu_k$ , between the object and the surface is approximately 0.127.

NOTE: This method is based on the principle of conservation of energy. It assumes that the only force doing work on the object (leading to a change in its kinetic energy) is the frictional force, with no other forces (like air resistance) at play.

How to Find the Coefficient of Kinetic Friction Using Mass and Force

When an object is in motion on a horizontal surface and you know the force being applied to it and its mass, you can determine the coefficient of kinetic friction ( $μ k $ ) between the object and the surface. Let’s delve into the process step by step.

Frictional Force

The frictional force acting against the motion of an object on a horizontal surface can be given by:

$F_{friction} = mu_k N$

Where:

$N$ is the normal (perpendicular) force. On a horizontal surface, $N = mg$ , where $m$ is the mass of the object and $g$ is the acceleration due to gravity (approximately $9.81 , text{m/s}^2$ ).

Net Force Acting on the Object

If a force ( $F$ ) is being applied to the object to keep it moving at a constant velocity on the horizontal surface, the net force is zero (since there’s no acceleration). This means that the applied force $F$ is balanced by the frictional force:

$F = F_{friction}$

Finding $μ k $

Using the above equations, we can express $F$ in terms of $μ_{k}$ :

$F = mu_k mg$

From this equation, we can solve for $mu_k$ :

$mu_k = frac{F}{mg}$

Worked-out Example

Let’s consider an object with a mass of $10 , text{kg}$ being pushed on a horizontal surface. To keep the object moving at a constant velocity, a force of $20 , text{N}$ is applied. Determine the coefficient of kinetic friction, $mu_k$ , between the object and the surface.

Using the derived formula:

$mu_k = frac{20}{10(9.81)}$

$mu_k approx frac{20}{98.1}$

$mu_k approx 0.204$ (rounded to three decimal places)

Thus, the coefficient of kinetic friction, $mu_k$ , between the object and the surface is approximately 0.204.

NOTE: This approach assumes that the object is moving at a constant velocity, which means there’s no acceleration and the net force acting on it is zero. This is crucial because it lets us equate the applied force with the frictional force.

Frequently Asked Questions

Does the calculation of kinetic friction without mass give the same value of coefficient obtained by considering the mass?

Yes, the value of the coefficient of kinetic friction with or without considering the mass is the same.

Since friction is a quantity that is independent of the absolute mass of the system, the mass does not affect the value of the friction involved in the process. Hence the coefficient of kinetic friction remains unchanged with or without considering the mass of the object.

Does the nature of the material influence the coefficient of kinetic friction?

The coefficient of kinetic friction is a numerical value that gives the evidence for the presence of friction force between the objects.

Since friction is influenced by the nature of the material, it is so evident that its coefficient is also largely influenced by the nature of the material.

What is necessary to find the coefficient of kinetic friction of a moving object?

Without the coefficient of kinetic friction, it is quite difficult to measure the force that makes the object to hinders its motion.

The friction is always proportional to the normal perpendicular reaction between the surfaces. This proportionality relation is specified by the dimensionless quantity called the coefficient. The coefficient of kinetic friction measures the absolute value of the friction force that stops the moving object.

Can the value of the coefficient of kinetic friction be greater than 1?

Generally, the value of the kinetic friction coefficient ranges from 0 to 1. Sometimes it gives a value of coefficient exceeds 1.

If the influence of friction force is stronger than the perpendicular reaction between the two moving surfaces, the value of kinetic friction coefficient exhibit the value greater than 1. Maximum frictional force makes the object to restrict its motion so that automatically the coefficient of kinetic friction increases proportionally.

Does greater coefficient of kinetic friction lead to energy dissipation?

The dissipation of energy due to friction can be described in terms of energy conservation Law.

A greater coefficient of kinetic friction means the friction force is stronger than the applied force. The challenging task is to keep the body in motion in the presence of friction. Hence it takes much force to keep the body in motion. The maximum force exerted to keep the body in motion causes the kinetic energy dissipation released in the form of heat.

What is the coefficient of friction?

A: The coefficient of friction is a dimensionless quantity that represents the ratio of the force of friction between two objects to the force pressing them together.

How can I calculate the coefficient of friction?

A: The coefficient of friction can be calculated by dividing the force of friction by the normal force acting on the object.

What is the difference between kinetic and static friction?

A: Kinetic friction occurs when two objects are in relative motion, while static friction occurs when there is no relative motion between the two objects, i.e., the objects are at rest.

What is the formula for the coefficient of kinetic friction?

A: The formula for the coefficient of kinetic friction is μk = Fk/N, where μk is the coefficient of kinetic friction, Fk is the force of kinetic friction, and N is the normal force.

How can I find the coefficient of kinetic friction for a moving object on a flat surface?

A: To find the coefficient of kinetic friction for a moving object on a flat surface, you can use the equation μk = tan(θ), where θ is the angle between the force of kinetic friction and the force perpendicular to the surface.

What is the equation for calculating the force of kinetic friction?

A: The equation for calculating the force of kinetic friction is Fk = μkN, where Fk is the force of kinetic friction, μk is the coefficient of kinetic friction, and N is the normal force.

How can I find the coefficient of static friction?

A: The coefficient of static friction can be found by dividing the maximum force of static friction by the normal force.

What is the relationship between the coefficients of static and kinetic friction?

A: The coefficient of static friction is generally greater than the coefficient of kinetic friction for a given pair of surfaces.

How can I solve a friction problem using the coefficient of friction?

A: To solve a friction problem using the coefficient of friction, you can set up equations based on the friction equation and other relevant equations, and solve for the unknown variables using algebraic methods.

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How To Calculate Kinetic Friction:Exhaustive Insights

January 21, 2024November 24, 2021 by Keerthi Murthi

Friction is a force that opposes the motion of an object when it comes into contact with another surface. It plays a crucial role in our daily lives, affecting the way objects move and interact with each other. Kinetic friction, specifically, refers to the frictional force between two surfaces when they are in relative motion. In this blog post, we will explore how to calculate kinetic friction, including identifying the necessary variables, step-by-step calculation process, and worked-out examples. We will also discuss special cases in calculating kinetic friction and how to determine the coefficient of kinetic friction.

How to Calculate Kinetic Friction

Identifying the Necessary Variables

Before diving into the calculation of kinetic friction, it’s essential to identify the variables involved. These variables include:

Coefficient of kinetic friction $\(\mu_k$ ): This value represents the interaction between the surfaces in contact and determines the amount of friction present.
Normal force (N): The force exerted by a surface perpendicular to the object in contact. It is equal to the weight of the object if no other vertical forces are acting on it.
Applied force (F): The force applied to the object in the direction of motion.

Step-by-Step Process of Calculating Kinetic Friction

To calculate the kinetic friction force $\(f_k$ ), we can use the following formula:

$f_k = \mu_k \cdot N$

The steps to calculate kinetic friction are as follows:

Determine the coefficient of kinetic friction $\(\mu_k$ ) between the two surfaces in contact.
Calculate the normal force (N) exerted on the object.
Multiply the coefficient of kinetic friction $\(\mu_k$ ) by the normal force $N) to obtain the kinetic friction force (\(f_k$ ).

Worked Out Example: Calculating Kinetic Friction

Let’s work through an example to better understand how to calculate kinetic friction. Consider an object with a mass of 10 kg resting on a horizontal surface. The coefficient of kinetic friction between the object and the surface is 0.5. If a force of 20 N is applied horizontally to the object, what is the magnitude of the kinetic friction force?

Determine the normal force N: Since the object is on a horizontal surface and no other vertical forces are acting, the normal force is equal to the weight of the object, which is $\(N = mg = 10 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 98 \, \text{N}$ .
Calculate the kinetic friction force $\(f_k$ ): Using the formula $f_k = \mu_k \cdot N$ , we have $f_k = 0.5 \times 98 \, \text{N} = 49 \, \text{N}$ .

Therefore, the magnitude of the kinetic friction force is 49 N.

Special Cases in Calculating Kinetic Friction

Calculating Kinetic Friction on an Incline or Slope

When dealing with a surface inclined at an angle, the calculation of kinetic friction becomes slightly more complex. In addition to the variables mentioned earlier, we need to consider the angle of the incline $\(\theta$ ). The formula to calculate the kinetic friction force on an incline is as follows:

$f_k = \mu_k \cdot N \cdot \cos(\theta)$

Here, the normal force N is equal to $\(mg \cdot \cos(\theta)$ , where $m$ is the mass of the object and $g$ is the acceleration due to gravity.

Calculating Kinetic Friction without Coefficient

In some cases, the coefficient of kinetic friction may not be provided. However, it is still possible to calculate the kinetic friction force using other known variables. One approach is to use the equation of motion:

$f_k = m \cdot a$

Where $m$ is the mass of the object and $a$ is the acceleration.

Calculating Kinetic Friction from Static Friction

If the object is initially at rest and then starts moving, we can determine the kinetic friction force using the static friction force. The static friction force $\(f_s$ ) is the force required to overcome the initial resistance to motion. Once the object starts moving, the static friction force transitions into kinetic friction. Therefore, the kinetic friction force $\(f_k$ ) is equal to the magnitude of the static friction force.

How to Determine the Coefficient of Kinetic Friction

The coefficient of kinetic friction is an essential factor in calculating kinetic friction. It provides information about the interaction between the two surfaces and determines the amount of friction present. There are different ways to determine the coefficient of kinetic friction, depending on the given variables.

Finding the Coefficient of Kinetic Friction with Mass and Force

If the mass $\(m$ ) and the applied force $\(F$ ) are known, the coefficient of kinetic friction can be determined using the formula:

$\mu_k = \frac{f_k}{N} = \frac{f_k}{mg}$

Where $f_k$ is the kinetic friction force, $N$ is the normal force, $m$ is the mass of the object, and $g$ is the acceleration due to gravity.

Finding the Coefficient of Kinetic Friction when Given Acceleration

If the acceleration $\(a$ ) of the object is known, the coefficient of kinetic friction can be determined using the equation of motion:

$f_k = m \cdot a$

Substituting the formula for the kinetic friction force $\(f_k = \mu_k \cdot N$ ), we get:

$\mu_k \cdot N = m \cdot a$

From this equation, we can solve for $\mu_k$ :

$\mu_k = \frac{m \cdot a}{N} = \frac{m \cdot a}{mg}$

Worked Out Example: Determining the Coefficient of Kinetic Friction

how to calculate kinetic friction — Image by Casint – Wikimedia Commons, Wikimedia Commons, Licensed under CC BY-SA 4.0.

Let’s work through an example to illustrate how to determine the coefficient of kinetic friction. Suppose an object with a mass of 5 kg is moving with an acceleration of 2 m/s². If the normal force is 40 N, what is the coefficient of kinetic friction?

Using the formula $\mu_k = \frac{m \cdot a}{N}$ , we can calculate:

$\mu_k = \frac{5 \, \text{kg} \times 2 \, \text{m/s}^2}{40 \, \text{N}} = 0.25$

Therefore, the coefficient of kinetic friction is 0.25.

By understanding how to calculate kinetic friction and determine the coefficient of kinetic friction, we can better analyze and predict the behavior of objects in motion.

How does kinetic friction impact the work done by friction?

The concept of kinetic friction plays a crucial role in understanding the work done by friction. When an object moves against a surface, kinetic friction opposes its motion by exerting a force. This force, along with the displacement of the object, determines the work done by friction. To delve deeper into how friction impacts work and motion, it is worth exploring the article on Friction’s impact on work and motion. The linked content provides valuable insights into the relationship between friction, work, and the resulting impact on objects in motion.

Numerical Problems on how to calculate kinetic friction

Problem 1:

A block of mass $m$ is placed on a horizontal surface. The coefficient of kinetic friction between the block and the surface is $\mu_k$ . The block is pushed with a force $F$ . Determine the magnitude of the force required to keep the block moving at a constant velocity.

Solution:

The force of kinetic friction can be calculated using the equation:

$f_k = \mu_k \cdot N$

where $f_k$ is the force of kinetic friction, $\mu_k$ is the coefficient of kinetic friction, and $N$ is the normal force.

Since the block is on a horizontal surface, the normal force is equal to the weight of the block:

$N = m \cdot g$

where $m$ is the mass of the block and $g$ is the acceleration due to gravity.

Substituting the value of $N$ in the equation for $f_k$ , we get:

$f_k = \mu_k \cdot m \cdot g$

To keep the block moving at a constant velocity, the force applied, $F$ , must be equal to the force of kinetic friction:

$F = f_k$

Therefore, the magnitude of the force required to keep the block moving at a constant velocity is:

$F = \mu_k \cdot m \cdot g$

Problem 2:

A car of mass $m$ is traveling on a horizontal road with a velocity $v$ . The coefficient of kinetic friction between the tires of the car and the road is $\mu_k$ . Determine the minimum stopping distance of the car if the brakes are applied.

Solution:

The force of kinetic friction acting on the car when the brakes are applied can be calculated using the equation:

$f_k = \mu_k \cdot N$

where $f_k$ is the force of kinetic friction, $\mu_k$ is the coefficient of kinetic friction, and $N$ is the normal force.

Since the car is on a horizontal road, the normal force is equal to the weight of the car:

$N = m \cdot g$

where $m$ is the mass of the car and $g$ is the acceleration due to gravity.

Substituting the value of $N$ in the equation for $f_k$ , we get:

$f_k = \mu_k \cdot m \cdot g$

The deceleration of the car, $a$ , can be calculated using the equation:

$a = \frac{f_k}{m}$

The minimum stopping distance of the car, $d$ , can be calculated using the equation:

$d = \frac{v^2}{2a}$

Substituting the value of $a$ in the equation for $d$ , we get:

$d = \frac{v^2}{2 \cdot \frac{f_k}{m}}$

Simplifying the equation, we have:

$d = \frac{v^2 \cdot m}{2 \cdot f_k}$

Therefore, the minimum stopping distance of the car is:

$d = \frac{v^2 \cdot m}{2 \cdot \mu_k \cdot m \cdot g}$

Problem 3:

A block of mass $m$ is placed on an inclined plane with an angle of inclination $\theta$ . The coefficient of kinetic friction between the block and the inclined plane is $\mu_k$ . Determine the acceleration of the block as it slides down the inclined plane.

Solution:

The force of gravity acting on the block can be resolved into two components:

The component parallel to the inclined plane, $mg \cdot \sin<img src=$ ” title=”Rendered by QuickLaTeX.com” height=”127″ width=”692″ style=”vertical-align: -6px;”/>
The component perpendicular to the inclined plane, $mg \cdot \cos<img src=$ ” title=”Rendered by QuickLaTeX.com” height=”127″ width=”692″ style=”vertical-align: -6px;”/>

The force of kinetic friction acting on the block can be calculated using the equation:

$f_k = \mu_k \cdot N$

where $f_k$ is the force of kinetic friction, $\mu_k$ is the coefficient of kinetic friction, and $N$ is the normal force.

The normal force, $N$ , can be calculated using the equation:

$N = mg \cdot \cos(\theta)$

The net force acting on the block can be calculated using the equation:

$F_{net} = mg \cdot \sin(\theta) - f_k$

The acceleration of the block, $a$ , can be calculated using Newton’s second law:

$F_{net} = ma$

Substituting the values of $F_{net}$ and $f_k$ in the equation for $a$ , we get:

$mg \cdot \sin(\theta) - \mu_k \cdot mg \cdot \cos(\theta) = ma$

Simplifying the equation, we have:

$a = g \cdot (\sin(\theta) - \mu_k \cdot \cos(\theta))$

Therefore, the acceleration of the block as it slides down the inclined plane is:

$a = g \cdot (\sin(\theta) - \mu_k \cdot \cos(\theta))$

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Types Of Harmonic Oscillator: Exhaustive Insights and Facts

January 21, 2024November 23, 2021 by Keerthana Srikumar

Types of harmonic oscillator are categorized into several types based on their function ability having a back and forth motion which is usually displaced from its equilibrium position that experiences a restoring force.

Types of harmonic oscillator are as mentioned below:

Simple Harmonic Oscillator
Damped Harmonic Oscillator
Quantum Harmonic Oscillator

Simple Harmonic Oscillator

A simple harmonic oscillator is one of the types of harmonic oscillator. The back and forth periodic motion from the equilibrium position is also known as simple harmonic motion.

The motion experienced by a system in simple harmonic oscillator is periodic. For example, we consider a pendulum that is suspended from the equilibrium position moves back and forth before coming to rest. The motion back and forth decreases with a decrease in amplitude.

In this type of simple harmonic motion, the restoring force is and the magnitude with how much the body experiences motion is proportional to each other when supplanted from its equilibrium position. The restoring force acting upon the object is simply the force used to stop the vibration.

Examples to better understand simple harmonic oscillators

Oscillating Pendulum: A pendulum is a mass suspended from a fixed, rigid support. When a push is given, the system experiences a vibration back and forth from its equilibrium position. This oscillation is periodic and goes by simple harmonic motion.

When a restoring force acts on the oscillations, it decreases as the amplitude decreases and ceases. This oscillation is known as simple harmonic motion.

Types of harmonic oscillator — “Pendulum / giant pocket watch – The Minories” by ell brown is licensed under CC BY 2.0

Another example of the simple harmonic motion is the park swing that we notice in parks. These swings remain at rest until and force acts on them to start the movement. When a person sits on it and starts to swing, it starts the motion.

Swings, when given a slight push, displace from their equilibrium position and move back and forth. This motion is periodic, and also simple harmonic oscillations occur.

14182557265 24358cd6f0 b — “Swings” by halfrain is licensed under CC BY-SA 2.0

Damped Harmonic Oscillator

Damping is the restriction of vibrations and oscillations in an equilibrium system by dissipation of energy. Damping oscillators are the ones in which vibrations decrease with time.

In a damping harmonic circuit, oscillations go on over a long period until and unless a restoring force is acted upon the equilibrium system. This restoring force is one of the reasons for the oscillation’s decay over time.

Damping harmonic oscillators are sub-divided into three types according to its damping factor. The system is said to be critical damping when the damping factor is equal to one. When the damping factor is more than one, it is called overdamped or high damping. The system is said to be underdapmed if the damping factor is less than one.

The damping formula is connected to the Newton Second Law, and according to it, the formula goes like this for any damped harmonic oscillator.

C2 – 4mk = overdamped

C2 – 4mk = critically damped

C2 – 4mk = underdamped

The damping factor for a damping harmonic oscillator is that the vibrations return to zero at the shortest time interval. The system undergoes a harmonic motion; when a restoring force is applied, the oscillations eventually come to rest or back to the equilibrium position in less time interval.

The damped harmonic oscillation is one of the types of harmonic oscillator. An excellent example of damped oscillations is the weight suspended by spring. When the weight is suspended, it displaces from the equilibrium position back and forth and comes to rest eventually.

Harmonic oscillations are the reason for some systems to function with proper back and forth movements. We often tend not to notice the daily events occurring, but we see the harmonic oscillations in them.

Quantum Harmonic Oscillator

Quantum harmonic oscillator is analogical to conventional oscillators. Quantum harmonic oscillator is generally dealt with quantum mechanics. The built-in configuration of a quantum harmonic oscillator is different from the classical harmonic oscillator.

Since the built-in difference for both quantum harmonic oscillator and classic harmonic oscillator, there will be changes in the functionality of any system that comes under any of these oscillators.

Quantum harmonic oscillator models the vibrations in micro-level systems. For example, in quantum optics the representation of the behaviour of vibrations in molecules or molecular levels, wave packets is possible with quantum harmonic oscillators.

In this quantum harmonic oscillator the energy level is said to be evenly spaced without being a continuous one.

Differences in Quantum Harmonic Oscillator

The motion in the quantum harmonic oscillator is similar to the motion in classical harmonic oscillators with few differences. The oscillation or vibration in quantum harmonic oscillator is explained better using Schrodinger’s equation.

Since the built-in difference for both quantum harmonic oscillator and classic harmonic oscillator, there will be changes in the functionality of any system that comes under any of these oscillators.

In this quantum harmonic oscillator the energy level is said to be evenly spaced without being a continuous one.

Frequently Asked Questions

What is the use of harmonic oscillators?

Harmonic oscillators are used in a system to decay the oscillations in a system.

The harmonic oscillators in a system are periodic, and it decreases with the decrease in amplitude. The back and forth motion in a system goes on for a long time until a restoring force is applied to the system.

Why do we use a harmonic oscillator?

A harmonic oscillator is used so that the system comes to the equilibrium position in a concise span.

When the system is undergoing a motion, it will come to rest when a force is applied, and that force is known as restoring force. The oscillations in the system will come to rest or the equilibrium position with decreasing amplitude.

Mention the difference between simple harmonic motion and oscillations?

Simple harmonic motion is period, but oscillations vary.

In simple harmonic motion, the restoring force acting upon the system is not been mentioned. In oscillations, the force which helps decay the oscillations called as restoring force is generally not mentioned.

How is harmonic motion explained?

Harmonic motion is a periodic motion and is explained using a sine wave.

The oscillations of a vibrating system decay with decrease in amplitude. The oscillations undergo some change that is, they will face a restoring force or negative force. This force acts opposite to the motion in which system acts.

Hence, the restoring force and displacement of an oscillating body form the equilibrium position are proportional. One of the types of harmonic oscillator which is the damped harmonic oscillator and this is explained using Newton Second Law.

What is an electric oscillator?

An electric oscillator is the ones that produces electric signals in a circuit in which it is been fabricated and these signals are usually sine wave or square wave.

An excellent example of an electric oscillator is harmonic motion. This electric oscillator converts direct current into alternating current. It produces continuous waveforms without any input. Simple harmonic motion is one of the great examples of harmonic oscillations.

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Gear vs Pulley:Exhaustive Detailed Insights

January 21, 2024November 20, 2021 by Keerthi Murthi

Both pulley and gear carry the rotating motion between the two objects via rope, string, or belt.

The way of working of both gear and pulley are pretty similar. But some of the properties may change. The comparison analysis of gear vs pulley gives an account of the difference and similarities.

Comparison between gear vs pulley

The comparative analysis of gear vs pulley is given in the table below, which may help you understand gear and pulley properties.

	Gear	Pulley
Definition	The gear consists of two rotational shafts fitted with the interlocking tooth-like structures placed in an equal interval.	Pulley consists of the simple wheel or axel in which the rope or a cable moves over.
Torque	The transmission torque acting on the gear is always greater.	Since the pulley uses the string for the transmission, the torque depends on the tension acting on the string. So the transmission of torque is less.
Tension	The gear does not need any medium for transmitting the motion, so the gear system is free from the tension.	The rope or cable used in the pulley exerts tension force, which affects the motion transmission
Distance	Gears are employed, where the transmission of motion takes place in a short distance.	Pulleys are employed to transmit the motion of a longer distance.
Power loss	There will be a loss in power during transmission.	The loss of power is relatively less in the case of the pulley system.
Change in the direction	The gear can reverse the direction of the motion by turning the two shafts in the opposite direction.	Pulley can also reverse its direction by moving the load along the circumference of the wheel or axel.
Speed	The gear offers a high speed of rotation.	It isn’t easy to achieve high speed in the case of a pulley.
Lubrication	Lubrication has to be done on the gear system regularly to work efficiently.	The pulley does not require any lubrication for its better performance.
Safety	The use of a gear system is safe for transmitting the motion as the gear does not slip.	Safety in the pulley system is lesser compared to the gear system because the pulley rope slip often.
Maintenance	The cost of maintenance of the gear is more, and it has longer life.	The maintenance cost of the pulley is less, and it has a shorter life span.
Nature of the equipment	The equipment used in gear is bulky.	The pulley uses lightweight equipment.
Efficiency	The efficiency of the gear is more because power loss is less.	The efficiency of the pulley is less because there is a loss of power due to friction and tension.
Purpose	The purpose of using the gear in the mechanical system is to change the direction and speed of the system.	The purpose of the pulley is to lift the massive object, and it can also change the direction.

Some need to know facts

Both gears and pulleys exhibit rotational motion.
Gears are continuously operated in pairs.
Pulley does not provide the mechanical energy on its own it just transfers the motion.
Gear uses parallel shafts for the operation.
Gears are employed in machines, automobiles, clocks and in some manufacturing tools.
Gears are available not only in a circular shape; they have come in cone and square shapes also.

Frequently Asked Questions

What is the major advantage of gears over pulleys?

The major advantage of using gear is to achieve constant velocity.

Even though the pulley covers a more considerable distance but it is difficult to achieve constant velocity. An additional force of “friction” is acting on the pulley, which reduces the torque so that the velocity keeps changing. But in the case of gear, torque is more so we can achieve the constant velocity.

Which is more efficient, pulley or gear?

The efficiency of the gear is more than the pulley.

Since the torque acting on the gear system is more, it offers more efficiency, about 99%, but the pulley offers an efficiency of 94-96%. It is because the pulley may slip so that there will be a loss of transmission power.

What are the advantages of pulley over gear?

A pulley can be operated at a longer distance also. This is one of the main advantages of the pulley over gear.

A pulley is a simple mechanical system that can be employed easily compared to the gear. And pulleys are not too bulky to carry. And the main advantage of the pulley is that lubrication is not needed for the efficient functioning of the pulley. To change the ratio of driving and driven pulleys are more suitable than the gear.

Why is lubrication mandatory for the operation of gear?

Lubrication is the method of oiling the gear system for better performance.

Lubrication prevents the friction between the teeth of the gear system, and it controls the rise in the temperature produced due to rolling and sliding friction between the teeth.

Explain the working of gear.

A gear is a wheel with a tooth-like structure that transfers the mechanical energy from one system to another.

The gear is provided with two axels. The one is the driving wheel, and the other is the driven axel—both consisting of teeth-like structures. If the first wheel rotates in the clockwise direction, the second one also rotates in the same direction by locking the tooth of one another. These wheels turn by interlocking teeth and promote mechanical energy.

How does torque influence the gear to promote the transmission?

In order to bring the gear in motion, torque is an essential component of the gear.

Torque involved in the gear reduces the internal friction between the teeth of the axels. Hence the rotational speed increases this made to increases the mechanical transmission of motion. So that efficiency of the gear also increases proportionally.

What are the factors involved in the energy loss in a pulley?

The factor involved in the energy loss in the pulley are given below

Friction – since the pulley does not need any lubrication, there will be a regular frictional force between the wheel and the cable; this reduces the energy of the pulley.

What are the disadvantages of the gear?

As the gear has several advantages, but there are several disadvantages also.

The gears cannot be employed when a significant distance separates the two axels.
The gear system produces noise and vibration, which may sometimes affect efficiency.
The lubrication has to be done regularly for better performance.
These mechanical systems are not so flexible. It works in a limited area.

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Overdamped Vs Critically Damped: Comparative Analysis

January 21, 2024November 18, 2021 by Prajakta Gharat

difference between overdamped and critically damped oscillations

By knowing the concept of damping, we must understand the difference between overdamped vs critically damped oscillations.

To understand overdamped vs critically damped, one can say that a system that is overdamped goes slowly toward equilibrium, whereas a system that is critically damped moves as swiftly as possible toward equilibrium without fluctuating about it.

Now let us see a table below where all information has summarize to make a comparative analysis of overdamped vs critically damped oscillations.

Overdamped vs Critically Damped Oscillation:

Overdamped	Critically damped
Overdamping occurs when oscillations come to a halt after a significant period of time has passed since the resistive force was applied.	In oscillatory system, the oscillations come to a halt as soon as critical damping is reached.
If a system responds to a step-change input by taking up a new position, it can either fluctuate around the final position before settling to the new value, or it can gradually approach the new value over time.	At a given level of damping, the system does not actually oscillate; however, it may slightly exceed before returning to the final value.
By solving damped harmonic oscillator, the case of overdamping is given by, b²>4mk	By solving damped harmonic oscillator, the case of critical damping is given by, b²=4mk
In the case of Overdamping b is comparatively large than m and k	In the case of Critical damping b is just between over and underdamping
The roots of overdamping are real and distinct. Because the roots are real, overdamping is the simplest situation to solve mathematically.	The roots of critically damped oscillator are real and same.
The characteristic roots can be given as, -b+√(b²-4mk)/2m r₂=-b-√(b²-4mk)/2m	The characteristic roots of critical damping are given as, -b/2m, -b/2m.

The general solution for a critically damped oscillation can be given as follows:

$x(t) = (C_1 + C_2 t)e^{-\gamma t}$

Where:

$x(t)$ is the displacement at time ( t ).
$C_1$ and $C_2$ are constants determined by the initial conditions of the system.
$\gamma$ is the damping coefficient.
( e ) is the base of the natural logarithm.

This is the detailed comparative analysis of overdamped vs critically damped oscillation.

Image Credits: Image by Goran Horvat from Pixabay

Before understanding overdamped vs critically damped oscillations, let us begin with overview of damping oscillation.

We all are familiar with damping and we also know damping oscillation examples in our surrounding.

If a system responds to a step-change input by taking up a new position, it can either fluctuate around the final position, finally settling to the new value, or it can steadily approach the new value, taking its time.

The system doesn’t truly oscillate at a certain level of damping; however, it may slightly overshoot before immediately returning to the final value. This is critical dampening, and it’s typically the goal.

Damped Oscillator:

We know the damped harmonic oscillator equation can be given as:

With m > 0, b ≥ 0 and k > 0. It has characteristic equation

ms²+bs+k=0………. (2)

With characteristic roots

Depending on the sign of the term under the square root, there are three possibilities:

b²< 4mk (This is the case of Underdamping as b is comparatively small than m and k)
b²> 4mk (This is the case of Overdamping as b is comparatively large than m and k)
b²= 4mk(This is the case of Critical damping as b is just between over and underdamping)

Overdamping is the simplest situation to solve mathematically since the roots are real. Most people, however, perceive the oscillatory behaviour of a damped oscillator.

Here we will see the case of Overdamping and critical damping as we have to do comparative analysis of overdamped vs critically damped oscillation.

Overdamping (real and distinct roots):

When b²> 4mk , then the value under the square root will be positive and the characteristic roots will be real and distinct. In case of b²> 4mk the damping constant b should be comparatively large.

One thing to remember is that in this situation, the roots are both negative. You can know this by looking at equation (2). Because the quantity under the square root is assumed to be positive, the roots are real.

By using these roots to solve the equation (1),

The characteristic roots are:

Exponential solutions are:

Therefore, the general solution can be given as:

Let’s take a look at this from a physical point of view. When the damping is high, the frictional force is so high that the system cannot oscillate. Unusually, an unforced overdamped harmonic oscillator does not oscillate. Because both exponents are negative, any solution in this situation approaches x = 0 asymptotically.

Many doors have a spring at the top that closes them automatically. The spring is damped to control the rate at which the door closes. If the damper is powerful enough to overdampen the spring, the door will simply settle back to its mean position (i.e., closed) without oscillating, which is normally what is desired in this situation.

Critical Damping (real and same roots):

When b² = 4mk, then the value under the square root becomes 0 and the characteristic polynomials has same roots -b/2m , -b/2m.

Now by using the roots to solve equation (1) in this situation. Because we only have one exponential answer, we must multiply it by t to obtain the second.

Therefore, basic solutions are:

And the general solutions can be given as:

This does not fluctuate like the overdamped situation. It’s worth mentioning that picking b as the critical damping value for a fixed m and k results in the quickest return of the system to its equilibrium state.

This is frequently a desired feature in engineering design. This can be observed by verifying the roots, but we won’t go over the algebra that illustrates it.

So, in this article you have learned the comparative analysis of overdamped vs critically damped oscillations.

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17 Uses of pulley: Exhaustive Detailed Insights

January 21, 2024November 17, 2021 by Keerthi Murthi

Pulleys help us to perform the task efficiently. These simple systems are used everywhere around us. Some uses of pulley are listed below.

Use of pulley to lift water from the well
Elevator
Lifting cargos
Window curtains
Fans with chains
Cranes
Extended ladders
Gym equipment
In construction sites
Flag poles
Rock climbing
Birdfeeders
Fishing rod
Pulleys in a sailing boat
Escalator
Garage doors or shutter
Theatre system
Timing belts in Automobiles
Oil derricks

Uses of pulley to lift water from the well

The oldest uses of the pulley system is lifting water from the well. It uses the moveable pulley to draw the water from the well. The rope is tied with a bucket at one end, and another end is in the hand of the user, who pulls the water. The rope and the bucket are thrown into the well, and when the bucket is full of water, the user exerts a force on the other end of the rope. The pulley axel helps the user reduce the applied force to pull the bucket filled with water. Hence makes the complete drawing of water from the well easier.

Elevator

One of the best uses of pulleys in the engineering domain is an elevator. To lift the heavyweight, high tensile ropes are used. The elevator carries heavyweights that can move up and down quickly by the pulleys. The elevator consists of several motor systems that lift the object with the mechanism of the pulley system—in the absence of a pulley, lifting the object and moving becomes a bit complicated.

Image credits: Image by Elsemargriet from Pixabay

Lifting cargos

In order to transfer the objects from one floor to another floor of multi-story buildings, the lifting cargos are very helpful. It is difficult to lift the massive object manually is very difficult. The uses of a pulley equipped in lifting cargos completes the task quickly.

Image credits: Image by 2427999 from Pixabay

Window curtains

The window curtains move smoothly up and down due to the simple pulley mechanism. A cord is attached to the wheel of the pulley, and when the cord is pulled, the curtain rises up. It is the very simplest form of use of pulley in everyday life.

Fans with chain

Fans with chains use the pulley system for their operation. The fan is fitted with two chains or cables hanging at the bottom of the fan. If you pull one chain, it makes the fan turn on, and the other one makes the fan turn off when it is pulled.

Cranes

In the construction of tall building or to lift the heavy object to greater height or to lift the vehicles the cranes are widely used. The cranes use a pulley mechanism to lift the thing. It consists of raising rope, chains, and sheaves. When the force is applied to these cables and chains, the crane lifts the object. Modern cranes are designed in such a way that they can lift complex materials beyond human capacity.

Image credits: Image by Ulrike Mai from Pixabay

Extended ladders

The most conventional uses of pulley is the extended ladders that you can see everywhere. The painters and the carpenters widely use this ladder. The rung lock system of the ladders uses the pulley mechanism. The lower end of the rung lock is fitted with the cord. This cord is extended to the top of the ladder by crossing over the pulley. The ladder can extend to a certain height by these pulley systems. Since the cord is extensible, we can easily adjust the height of the ladder accordingly.

Gym equipment

Certain gym and exercise tools make uses of pulleys in their mechanism. This equipment uses moveable pulleys for their operation. The one end of the string in the equipment is attached to the weights, and another end is given to the user through a pulley. When the user pulls the string, the string exerts the tension force, which is transferred to the body. It helps in strengthening the muscle. Not only gym equipment but some athletic training tools are also involved in the use of pulley systems.

Image credits: Image by Total Shape from Pixabay

In construction sites

Uses of pulley mechanism is very common in the construction. Since the pulleys are made to lift the massive object, pulleys are widely used in construction sites. The pulleys help to lift and dumping of the materials used for the construction. Most commonly, block and tackle pulleys are used in construction sites. The gun tackle and yard and stay tackle pulleys are widely used.

Flag poles

Another widespread uses of a pulley is a flag pole. We can not hoist the flag without a pulley. Since the flag pole is tall, a rope is tied to the flag pole along with the pulley. To unfold the flag at the top of the pole, pulleys play a vital role. When the rope is pulled, the flag moves upwards with the pulley’s help, and when the rope is dragged, the flag opens. Hoisting the flag becomes effortless because of the use of pulleys in the process.

Rock climbing

The effective uses of the pulley system is rock climbing. It isn’t easy to climb the rock because the climber has to move against gravity. It needs to exert greater force to climb the rocks. Pulleys help to do this task with ease. The climbers have attached themselves to the climbing cord, which passes over the pulley. When the climber pulls the cord downwards, the climber moves upwards with the help of the pulley. This reduces to exerting more force to climb.

Birdfeeders

The uses of pulleys are extended in the birdfeeders also. These birdfeeders are fitted with pulleys to keep the feeders at the top of the trees or poles.

It can be pulled down when it needs to be refilled. This significantly helps to feed the birds in the high trees.

Fishing rod

The fishing rods are used to catch the fishes is fitted with the pulley at the axel of the rod. The pulleys help to move the cable fitted with the hook to elongate as the axel rotates. This is the simplest form of pulley system. The modern fishing rods are formed by the gear system also.

Pulleys in a sailing boat

A simple pulley is used in the sailboats to lift the heavy sails and the cargos. Sailboat may use multiple pulleys for the lifting process. It consists of both fixed and moveable pulleys. One of the sailboats is fitted with a simple pulley and rope. When the rope is pulled downward direction, the other end of the boat is lifted. The use of pulleys also helps to ensure smooth sailing. It is because the bearing system uses the pulley mechanism in sailing boats and ships.

Escalator

The moveable steps or escalators you have seen in the shopping mall, railway station, and airports are make uses of pulley system and the gear system for their motion. The escalator’s handrail moves with the steps of the escalator when the passenger puts their hand on the handrail. At the back of the escalators, the pulleys are attached with the gears to move the escalator and the handrail to move together.

These pulleys provide tension to the escalator’s belt to rotate and move in the direction opposite to the applied force.

Garage doors or shutter

Garage doors are bulky to lift. It is a complex lift manually. The uses of a pulley system helps to move the shutter up and down. At the top of the doors, four pulleys are fitted connected to the weightless string. These pulleys help to make the process easier. When the shutter door pulls up, the exerted force applied to the pulley makes the string rotate, and the door moves up and down easily.

Theatre system

A simple curtain can be pulled manually, but raising the theatre curtain manually is highly impossible. In order to raise the curtain, several sets of pulleys are required, which are attached to the single cord. The uses of pulley helps to move the curtain upward when the cable is pulled down.

Timing belts in Automobiles

Certain parts of automobiles make uses of pulley systems for their better performance. A type of pulley called idler pulleys is widely used in vehicles. These pulleys are employed to provide tension to the drive belt. These pulleys operated against the belt direction so that the tension on the belt get reduced.

Oil derricks

Image credits: Image by Viola ‘ from Pixabay

In oil and petroleum industries, the uses of pulley systems can be found regularly. Usually, the pulleys are mounted at the top of the rig, or it can be seen in the running wire lines. To gain mechanical energy, the pulleys are arranged in blocks and tackle between the crown blocks and the traveling blocks. The block and tackle pulley provide sufficient mechanical energy to lift the heavy load. For the wireline operation, two pulleys are hung in the derrick, and the wireline runs smoothly.

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Coulomb Friction Vs Viscous Friction:Comparative Analysis

January 21, 2024November 17, 2021 by Keerthi Murthi

Friction is a force of resistance that retards the relative motion of the matter. Coulomb friction and viscous friction are the sub-division of friction force.

Though both Coulomb and viscous friction restrict the motion of the matter, they exhibit different natures. Comparing Coulomb friction vs. viscous friction leads to understanding how friction changes its properties with the matter.

Coulomb friction Vs Viscous friction

Both difference and similarities between coulomb and the viscous friction can be understood by comparative analysis. The below table gives the study of Coulomb friction vs. viscous friction.

Coulomb Friction	Viscous Friction
Coulomb friction is applicable for stiction (static friction).	Viscous friction is the another name for fluid friction.
Mass and volume are not the functions involved in the Coulomb friction.	In the case of Viscous friction, only the volume is considered; it does not depend on the mass.
Coulomb friction is zero when the speed of the surface is zero, and it moves proportional to non-zero for all values of speed.	Viscous friction directly corresponds to the speed at which the fluid flows.
The distance between the two contact surfaces makes a huge contribution to the Coulomb friction.	Since viscous friction depends on the velocity gradient, it is also influenced by the distance between the layers of the fluid.
The change in the temperature has a direct effect on the Coulomb friction.	The viscous friction is inversely influenced by the change in the temperature of the fluid.
It completely depends on the coefficient of friction of the surface.	The factor coefficient of friction does not involve in this process.
Due to the Coulomb friction evolved between the surfaces may produce heat in some cases.	Since viscous friction evolved between the two layers, it is completely an internal property and does not produce heat.
The occurrence of Coulomb friction is due to the adhesive force on the solid surface.	Cohesive force is responsible for the viscous force to occur.
The variation of Coulomb friction is due to only the relative motion between the two surfaces.	The deformation or movement of fluid layers in the viscous friction is due to the shear stress.

Definition of Coulomb Friction

Coulomb friction is a synonym for “dry friction.” It is exerted on the solid surface to restrict the lateral motion.

coulomb friction vs viscous friction — Image credits: Image by Rudy and Peter Skitterians from Pixabay

Dry friction was named coulomb friction after Charles Augustin de Coulomb proposed a model to calculate dry friction. He gives the expression of inequality as

F_f ≤ µF_n

Where; F_fis the friction force exerting between the two surfaces.

µ is the coefficient friction force. F_nis the normal force acting between the two surfaces.

Definition of viscous friction

Viscous friction is applied on the layers of both liquid and gas to restrict the relative flow of the fluid.

Image credits: Image by PublicDomainPictures from Pixabay

Frequently Asked Questions.

What are the factors that affect the coefficient of friction?

The factors that may affect the coefficient of friction are

The nature of the surface – for the smooth surfaces, the friction is less. But in the case of rough surfaces, the coefficient of friction is more compared to the smooth surface.

Temperature – the change in temperature and the coefficient friction are corresponding to each other. At higher temperatures, the coefficient of friction is also high.

What do you meant by cohesive and adhesive forces?

These are two different forces exerted on the substance can be define as below.

Cohesive force is a tendency of a substance that makes two particles of the same substance hold together by creating a force of attraction.
Adhesive force is a tendency of two dissimilar surfaces attracting one another to keep in contact with each other.

Does the coefficient of friction is applied to the viscous friction?

As the coefficient of friction is a dimensionless quantity and the viscous friction has a certain dimension. So coefficient friction is not applicable to viscous friction.

A quantity coefficient of viscosity is used to measure viscous friction. It is the ratio of shearing stress acting between the layers of the fluid and the relative velocity at which the fluid is flowing.

Does the pressure affect the viscous friction?

Under normal conditions, pressure does not affect the viscous friction acting on the fluid.

At high pressure, the intermolecular distance between the layers of the fluid decreases so that force between the molecules increases. This decreases the relative velocity between the two layers. This increases viscous friction.

A wooden block is sliding on the surface. Calculate the friction acting between the block and the surface if the normal force acting between them is 7N, and the coefficient of friction is 0.30.

Solution:

Given: Coefficient of friction µ = 0.30

Normal force F_N = 7N

The friction acting between the wooden block and the surface is given by

F = µF_N

F = 0.30 × 7

F = 2.1 N

The Coulomb friction acting on an object is 5.6N, and the normal force acting on the object is 8.1N. Find the coefficient of friction.

Solution:

Given: The friction force acting on the object is 5.6N

The Normal force acting between object and surface is 8.1N

The Coulomb friction acting on the object is given by

F_f = µF_n

5.6 = µ (8.1)

µ = 0.69

Can friction coefficient have a negative value?

Practically it is impossible for an object to have a negative value of the coefficient of friction.

In 2012, a study on the potential for friction demonstrated that for a low-load system, the normal force acting on the object and surface decreases which leads to an increase in the friction between the object and the surface. However, it contradicts the real-world experiment.

How does the distance between the two layers affect the viscous friction?

The distance between the two layers of the fluid directly corresponds to the change in the velocity between the two layers. It influences the viscous friction of the fluids.

When the fluid flows, the layers of the fluid exhibit distinct velocities. If the layers and the boundary of the fluid are closer, the shear stress acting at the boundary becomes maximum; this makes the velocity decrease. So the distance between the layers influences the viscous friction.

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Types Of Pulley:Exhaustive Insights

January 21, 2024November 17, 2021 by Keerthi Murthi

Pulley is a simple mechanical system that helps to transmit the motion of an object via rope, rod, or belt.

Pulley helps change the position and direction of an object easily. It is used only to transfer the object’s motion. It does not provide energy for the object to move. This post is concentrated on the types of the pulley.

Types Of Pulley

There are several types of pulley that are very helpful to carry the motion. The three basic types of the pulley are;

Fixed pulley
Moveable pulley
Compound pulley

Let us study these in detail.

Fixed pulley

It is one of the types of pulley system which has a pulley attached to a fixed arm and a rope is holding the weight is moving over the pulley. The fixed pulley is designed such that the wheel and the axel situate in one edge.

Working of a fixed pulley

When you pull the rope on one side, say downward, the other side of the rope moves in the upward direction. The force that you apply to pull the rope downward is equal to the force that you exert to lift the same object by your hand. In this case, the direction of force changes.

Moveable pulley

In this type of pulley consisting of a rope whose one end is fixed and other is set free to pull. This rope crosses over the pulley, which is attached to an object.

Working of moveable pulley

When the free end of the pulley is pulled down, the pulley slide over the string and uplift the object, this pulley is beneficial if you are at a higher altitude and the object is below your level. Moveable pulleys will work as wheel, if both the end of the string is fixed to the arm. In that case, when the force is applied, the object moves along the string.

Compound pulley

It is a type of pulley composed of both fixed and moveable pulley in a single system. It is employed to lift the heavy object. This pulley makes you exert less than half of the energy.

Image credits: Image by Muhammet Ali ÇETİN from Pixabay

Working of compound pulley

Since it has both fixed and movable pulleys, it makes the object lighter and becomes easy to lift. For this process, you need much speed. The compound pulley is also called as “Combinational pulley system.”

Other than the above three types, there are several types of pulley. The secondary types of pulley are

Block and Tackle pulley
Step pulley
Cone pulley
Jockey pulley
V groove pulley
Conveyor pulley
Belt pulley

Block and Tackle pulley

Block and tackle or simply tackle pulleys consists of two or more pulleys in a single system held by a rope or cable. This particular type of pulley is used to lift the massive body.

Working of block and tackle pulley

Several sets of pulleys combined together to form a block. This block, along with a rope crossing over the pulley, is called a tackle. These blocks are paired in such a way that one pulley is fixed and another is to be moveable. The load is attached to the moveable arm of the pulley. The rope provides mechanical support to the system and boosts the tension force on the rope to lift the massive body.

This type of pulley is commonly used in boats, cranes, and sailing ships.

Step pulley

A step pulley consists of several pulleys of various diameters fixed to one arm. It is arranged in such a way that it looks like a step, so the pulley is named a step pulley.

Working of step pulley

Step pulley is provided with a belt. The belt is changed from one step to another step to monitor the speed of the system. Step pulleys are always operated in pairs. When the belt of the one pulley is changed, the belt of other pulleys is also changed simultaneously. These pulleys are employed to regulate the speed of the pulleys.

This types of pulley is commonly equipped in the machines such as drilling machines, lathe machines, etc.

Cone pulley

It is a type of pulley that acts in pairs. Cone pulleys are usually narrow and cut into two parts. The pulleys are arranged as the broad end of the one cone is facing the narrow end of the other one. It is provided with a belt that moves with the pulley and controls the speed of the system.

Jockey pulley

A jockey pulley consists of a wheel at the top edge and a belt attached to it. This type of pulley is also used to regulate the speed of the machinery.

Working of jockey pulley

Jockey pulleys are fitted with five pulleys, which are operated by coupling with other pulley. While running the machine, the belt may become loose and slip from the pulley. The third pulley, a self-controlled pulley, is used in pairing with the two pulleys to overcome this problem.

V groove pulley

This typical types of pulley consists of a “V” shaped belt is used to move over the two pulleys. This is particularly equipped in automobiles and electric motors to transmit power between the parallel axels of the pulley.

Image credits: Image by b0red from Pixabay

Working of V-groove pulley

The V belt used in the system provides the mechanical linkage. This delivers excellent speed and load capacity to the system. Heavy load increases the efficiency by transmitting power through the belt, which is responsible for reducing friction.

Conveyor pulley

Conveyor pulleys are used for the driving purpose equipped in the countershaft of the machines. It consists of broad and flat belts on their face.

Working of conveyor pulley

It is type of pulley consisting of a roller and a flexible disc. The conveyor belt helps to change the direction of the pulley and provides tension. The disc and the roller are fitted in the end-to-end connection, which allows for rolling over the conveyor motors. These are used in the oil engine and electric motors.

Belt pulley

It is the most inexpensive pulley used in the computer printers, papermakers, and textile industries.

It consists of a flat belt that moves over a flat pulley. It is operated at high speed and uses low power. The torque acting on the pulley is more, so that, if the belt slipped, there would be very little damage to the equipment.

The belt pulleys are further classified into three types, they are

Split pulley
Wooden pulley
Paper pulley

Split pulley

It is a type of pulley. It is made up of cast iron, consisting of two parts, one is a face, and another is a hub. These are versatile pulley, operates efficiently in all size of the pulley. It is mainly used in saw machines and oil extraction.

Wooden pulley

The wooden pulleys are lightweight pulleys made up of wood. These are fitted with adjustable screws to reduce friction.

Paper pulley

In this type of pulley, the inner layer of the pulley is comprised of metal coat and outer layer is coated with the paper fibers. The paper fibers are compressible, and they transfer the motion from the center to the shaft in a short distance.

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What Is Wet Coefficient Of Friction: Facts and FAQs

January 21, 2024November 16, 2021 by Raghavi Acharya

The coefficient of friction is to find the ratio of friction present on the surface. In this article, we will know about what is wet coefficient of friction.

The wet coefficient of friction is one of the kinds of friction coefficients. It is mainly used to determine the magnitude of frictional force present on the wet and solid floors. It is a numerical value used to calculate the frictional coefficient when a body is in motion.

Let us know in detail about what is wet coefficient of friction.

Wet friction

Wet friction comes under the unique category of frictional force. It acts between two different types of surfaces.

Wet friction has comparatively less frictional force than dry friction because the arrangement of atoms/molecules in a liquid matter is loosely bound than solid, reducing frictional force. It acts between the concrete surface and a wet surface.

The name itself indicates the surface nature of wet friction.

What is Wet coefficient of friction

The wet coefficient of friction is used to determine the force of friction between the different surfaces.

The wet coefficient of friction is usually taken as the ratio of force of wet friction acting between the two objects in contact. It determines how much opposing force must be provided to an object to stop. It is usually observed between one solid and one wet surface. The strength of friction on wet surfaces is less compared to all other surfaces.

Now let us see some examples of the wet coefficient of friction.

Examples for a wet coefficient of friction

In general, we can observe wet surfaces in many places; all these wet floors contain some amount of frictional force. Here are some examples of the wet coefficient of friction.

Application of oil lubricants
Person diving into a river
Erosion of soil
Oil on window hinges
Holding objects with a wet hand

Application of oil lubricants

In general, we apply drops of oil lubricants to our vehicle engine to make it move freely with the more negligible effect of frictional force. It is an essential procedure used to maintain the texture of pieces of machinery. Here, the wet coefficient friction will be less after applying the lubricants.

what is wet coefficient of friction — Image Credit: Pixabay free images

Person diving into a river

If you observe a swimmer, you will see that he stretches out his hands while diving to maintain the balance to overcome the friction. It is necessary because it feels hard to move forward if the wet friction coefficient is high, so he has to maintain a streamlined position to move forward.

Erosion of soil

During heavy rainfall, there is a possibility of washing away an upper layer of soil. After the rain stops, the surface will be wet; here, we can observe wet friction, i.e., when we step the surface, it slips down, which may lead to a person’s falling. The slipping is possible only due to the low value of the coefficient of friction.

1200px Eroding rill in field in eastern Germany — Image Credit: Wikipedia

Oil on window hinges

It is common in the household to apply oil drops on the hinges of windows or doors to make the movement manageable. This easy moving of windows is due to less wet coefficient of friction between the solid window surface and the moist soil surface.

Holding objects with a wet hand

When you try to hold any object or material with your wet hands, it slips down easily. It is because of the lower value of the wet coefficient of friction. The wet friction comes into action since it is a wet surface, and you try to hold the solid object.

These are some essential daily life examples where we experience wet friction and its coefficient.

Factors affecting wet coefficient of friction

Many factors affect the frictional forces, which in turn affects the coefficients of friction. The elements are as follows;

It depends on the types of frictional force acting.
It depends on the nature of the contact surfaces.
It depends on the irregularities present in the two surfaces.
Pressure between the materials in contact.
It also depends on the area of the contact.

Those mentioned above are primary factors that affect the wet coefficient of friction.

Formula to calculate the wet coefficient of friction

A similar procedure used to calculate the coefficient of friction of fluid is used for wet surfaces.

The general formula is given below,

Where,

F refers to the wet frictional force

A refers to the surface area

= refers to the coefficient of wet friction

can also use the other formula to calculate the coefficient of wet friction.

F = N

Where,

= Coefficient of friction

This is the formula used in general to calculate the wet coefficient of friction.

Problems based on the wet coefficient of friction

Let us solve some problems based on the wet coefficient of friction to understand it better.

Problem 1

Calculate the wet friction coefficient if the value of F is given as 5N and the cross-sectional area is given as 12m, and the velocity gradient is given as 0.2/s?

Solution:

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5 = *12 * 0.2

= 5/12 * 0.2

= 2.08

Therefore, the coefficient of wet friction is 2.08

Problem 2

Calculate the wet friction coefficient if they have given the total wet frictional force 15N and the normal force acting on it is 18N?

Solution:

F = N

18 = * 15

= 18/15

= 1.2

Therefore, the coefficient of wet friction is 1.2

Frequently Asked Questions on the wet coefficient of friction | FAQs

Is the coefficient of friction and wet coefficient of friction similar?

The wet coefficient of friction is used to know the value of friction present on wet floors.

Both coefficients of friction and wet coefficient are comparatively the same. In the coefficient of friction, we find out a force of friction to be calculated irrespective of the surface, but in the case of the wet coefficient of friction, we estimate it on wet floors.

Is dry friction smaller than wet friction?

The dry friction of an object is always higher compared to wet friction.

Dry friction coefficient has a higher value compared to wet coefficient friction. The wet floor contains water, which exerts a less frictional force on the objects, leading them to slip. Even the arrangement of molecules plays a vital role in exhibiting frictional force.

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