How To Find Sliding Friction: Detailed Explanations


This article discusses about how to find sliding friction. We all know what friction means. It is the opposite force experienced by us when we are moving or trying to move an object.

In this article we shall study about different types of friction and their applications. We shall also study about sliding friction in detail. The sliding friction acts on an object when the two objects are sliding against each other. The sliding results in meshing of irregularities with each other. The meshing being the sole reason behind the sliding friction taking place.

What is friction?

As discussed in the above section, friction is the opposing felt when an object is moving or is about to move. The friction generates heat, hence we can say that kinetic energy is compensated by the heat generated.

The friction arises mainly due to the irregularities on the surface. The surfaces have tiny rough patches on it which mesh with the roughness of other object that is sliding on it. No object has an ideal surface they have certain irregularities for sure. Now when these irregularities mesh with each other, friction arises between them.

how to find sliding friction
Image: Friction between two surfaces

Image credits: CaoHaoFriction between surfacesCC BY-SA 4.0

What is sliding friction?

The friction that arises between two objects when they are sliding against each other is called as sliding friction.

As already discussed the irregularities on the surface of these objects are responsible for friction that is taking place. When the irregularities mesh with each other, bonding takes place due to which the objects slow down. This slowing down is referred to as the action of frictional force.

How to calculate co efficient of sliding friction?

Co efficient of sliding friction is the ratio of frictional force to the normal reaction force acting on the object by the virtue of its own weight.

We can calculate the co efficient of friction by the formula given below-

FssN

Where,

Mu is the co efficient of sliding friction

Fs is the sliding frictional force

N is the net normal reaction acting on the object

Co efficient of sliding friction

We have already discussed in the above sections that co efficient of friction is the ratio of frictional force acting on the object to the net normal reaction force acting on the object.

In simple terms it can be said that the co efficient of friction is the measure of roughness of the surface. Greater the value of co efficient greater will be the roughness of the surface and hence greater will be the value of frictional force. The formula of co efficient of friction is already discussed in the above sections.

Factors affecting sliding friction

Sliding friction is affected by a lot of factors, these factors are stated in the section given below-

  • The deformation of surface of the objects.
  • Roughness or smoothness of the surface of the objects.
  • Speed of either of the two objects or both the objects.
  • Size or mass of the object.
  • The amount of pressure on either of the object.

Examples of sliding friction

The sliding friction is so common that we can see it everyday around us. The most common examples of sliding friction are given below-

  • Rubbing of hands – Rubbing of hands against each other is an example of sliding friction. Both the hands slide against each other, sliding results in generation of heat. The heat is a result of friction taking place between the two hands.
  • Slides in playgrounds – When children play on slides, they tend to come down very fast, but this does not mean that no friction is taking place. Some amount of friction is always taking place between the slide and and the kids. The friction that takes place is called as sliding friction.
  • Sliding a book on table– When we slide a book on table, the book comes to rest after travelling a certain distance. This happens due to friction taking place between the book and the table. The friction taking place is the sliding friction.
  • Washing machine pushed on the floor– When we install a new washing machine and move it aside for adjusting it, we can feel a resisting force acting on the washing machine. This is sliding friction taking place between the washing machine and the floor.
  • A box being dragged – When a box is being dragged, the box experiences friction. This is the sliding friction taking place between the box and the floor.
  • Two cards being slided against each other– When we are shuffling a deck of cards, we observe that the cards slide on each other. Between these cards, sliding friction takes place.

Applications of friction

The friction is often seen in negative terms. But we should know that friction plays a very vital role in our lives. Some of the places where friction is desirable to us is shown in the section below-

  • Walking – We would not be able to walk if the floor is frictionless. The friction allows our legs to get a forward push with the normal reaction force acting on them. Without friction the legs will keep on sliding at one place without getting any significant displacement. Hence walking is an important application of friction.
  • Running – Just like walking, running also takes help of friction. Just as it happens in walking, the legs will slip on a smooth surface and we would not be able to run on a smooth surface. The friction will allow the legs to get a forward push through the normal reaction force. We have often seen that sprinters in races wear shoes having spikes. These spikes are used to increase the amount of friction acting on it.
  • Brakes – Brakes are the most important application of friction. Friction will help the vehicle to stop before it gets crashed into other vehicle or wall. The brakes are an important feature in every automobile. Even in aeroplanes we have brakes to stop the aero plane from over running the runway.
  • Cycling – Cycling takes help of the surface roughness to get a forward push. This can be explained by the looking at the surface irregularities on both the objects. These irregularities mesh with each other in order to get the forward push. Without meshing, the cycle will simply stand at one place as it would not get any forward push from the surface.
  • Pen grip – Pen’s grip is the most common application of friction. When we write without the use of grip, our fingers have a tendency to slip due to the smooth nature of the pen body. To avoid slipping, we use grip so that we can write without any difficulty.
  • Holding an object – Holding an object may seem to be a very normal thing but it requires friction to keep the object in hand. This is the reason why slippery things are so difficult to hold. Slippery things have very less roughness due to the action of lubrication. While a rough object is easier to hold as it provides better grip while holding.
  • Driving a car – Driving a car is similar to cycling, as the wheels experience friction in order to move forward. The wheels experience a forward push when the surface irregularities mesh with each other.
  • Gear meshing – Gears are circular wheels having teeth like structure on its circumference. These teeth act as irregularities on the wheel. When the teeth of two gear mesh with each other, motion is transmitted from one wheel to another. Usually one gear wheel is the driver and other is a follower.
  • Belt drive – Belt drive is also an application of friction. Belts have rubber grip on its surface. These belts are put on circumference of rotating wheels. When one wheel rotates, the belt also starts moving due to gripping action. The belt is connected to another wheel that also starts rotating due to the moving belt. This way motion transfer takes place in belt drive.

Abhishek

Hi ....I am Abhishek Khambhata, have pursued B. Tech in Mechanical Engineering. Throughout four years of my engineering, I have designed and flown unmanned aerial vehicles. My forte is fluid mechanics and thermal engineering. My fourth-year project was based on the performance enhancement of unmanned aerial vehicles using solar technology. I would like to connect with like-minded people.

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