How To Find Coefficient Of Static Friction: Detailed Explanations and Problem Examples 


In this post, we will analyze how to find coefficient of static friction and other aspects of this.  

The formula for finding the static friction coefficient is μs=FsN

where μs is static friction,  

Fs is the frictional force 

and  N is the normal force

The coefficient of friction is unitless and is expressed in force measurements (such as newtons or pounds). 

The coefficient of resistance is the proportion of the resistive pressure that restricts movement across two items in touch to the normal tension that moves the two plates along. The Greek symbol μ is generally used to represent it. 

For static resistance and dynamic resistance, the coefficient of friction has distinct amounts. The static friction pressure resists the resistive pressure applied to a body, and the body stays at rest till the fixed resistance pressure is reached. In kinetic impedance, the resistive force opposes an entity ‘s movement.

The coefficient of kinetic friction for a brick sliding on a clean hardwood table is around 0.5, implying that a force equal to half the load of the blocks is necessary only to overcome resistance and maintain the bricks rolling along at a steady pace, whereas the coefficient of stationary resistance is about 0.6. As the item moves, the resistive pressure is transferred in the reverse way. 

How to find the coefficient of static friction on an inclined plane? 

From a reference system with +x normal to the gradient and +y down the slope. Divide the gravitational force into x and y parts

Newton’s second law should be applied twice. As a consequence, the static friction coefficient is equivalent to the slope of the degree to which the objects move. Placing two items together and tilting them until the top one slides is a simple approach to determine the coefficient of static friction. The degree to which one item starts to fall on the another is related to the coefficient.  

There is zero frictional force whenever the surfaces are horizontal. The force of static friction must grow from zero when the items are gently tilted to counterbalance the part of gravity acting along with the contact. 

As the angle grows larger, that part of gravity finally reaches the maximum amount of static friction, and the upper item slips off. 

How to find coefficient of static friction from graph? 

By calculating the slope of the graph between Fs that is the frictional force and N that is the normal force. 

First, draw a graph between friction force on the positive y-axis and normal force on the positive x-axis. Make a line connecting all of the dots in the XY plane. The slope of that line will be the coefficient of friction as the coefficient of friction is equal to the ratio of Fs that is the frictional force and N that is the normal force. 

How to find coefficient of static friction with velocity and radius?

By substituting the value of normal force with the product of the mass of the body and acceleration due to gravity. 

From the formula we know that static friction is  μs=FsN

Also, N= mg

And we know centripetal force, F=mv2/r

Therefore, μs=mv2/r/mg

Hence, μs=v2/gr

How to find coefficient of static friction on a horizontal surface? 

A body should have static friction , μs=v2/gr velocity (v)v, radius (r)r to move it around a curve. 

Static friction is the resistance that happens whenever an item is placed on a substrate. Kinetic friction is caused by an item moving over a surface. 

A useful approach to explain friction is the coefficient of friction, which is described as the proportion of the resistive pressure to the normal pressure.   Static friction refers to the amount of resistance on a fixed item. This aids the object’s ability to rest on a surface. A static friction coefficient is a scalar number symbolized by the letter  μs

How to find coefficient of static friction with mass? 

By replacing the value of normal force with weight 

We know that static friction is μs=FsN. here we can substitute value of normal force into weight that is product of mass of body and acceleration due to gravity (N=mg)

This is how the friction factor with mass is calculated.  

How to find coefficient of static friction without mass? 

By using velocity (v) radius(r) to move it around a curve and acceleration due to gravity(g)

From the formula we know that static friction is μs=FsN

From the formula we know that static friction is  μs=FsN

Also, N=mg

And we know centripetal force, Fs=mv2/r

Therefore,  μs=mv2/r/mg

Hence, μs=v2/gr

so, a body should have static friction   μs=v2/gr

Problems 

Problem 1 

A 5-kilogram body is put on a flat surface. The 20 N represents the static friction across the two surfaces. What is the static friction coefficient? 

Solution: 

First, we will write the given values in problem 

Given 

mass, m = 10 kg 

Static friction, F = 20 N 

Coefficient of friction μs=?

We know that, 

Normal force, N = mg 

So, N = 5× 9.81 =49.05 N 

The formula for coefficient of static friction is, 

 μs=FsN

μs=20/49.5

μs=0.40

Therefore, coefficient of static friction is 0.40 

Problem 2 

An item’s normal force and static frictional forces are 20 N and 50 N, respectively. What is the static friction coefficient? 

Solution: 

Given values are, 

Normal force, N= 20N 

Static friction or frictional force, F= 50N  

Coefficient of friction,  μs=?

From the formula of coefficient of static friction,  

μs=FsN

 μs=50/25

 μs=2.5

Therefore, coefficient of static friction is 2.5 

Frequently asked questions |FAQs 

Ques. What is static friction? 

Ans. It is a force. 

Static friction refers to the amount of friction on a fixed entity. If you press on a motionless object and it doesn’t move, it’s because static friction is equivalent to and contrary to your press. 

Ques. What is kinetic friction and what does it mean? 

Ans. When two things move with each other and scrape along, this is referred as kinetic friction, also termed as dynamic friction or sliding friction (like a sled on the ground). 

Ques. Do static and kinetic friction coefficients have the same value? 

Ans. Kinetic Friction: The force needed to start a movement is always larger than the power needed to keep it going. As a consequence, dynamic resistance has a lower coefficient than static friction. What exactly is this? Static Friction: The static friction coefficient is higher than the dynamic resistance coefficient in this case.  

Ques. What’s the difference between static and kinetic friction coefficients? 

Ans. Since there are larger forces retaining an entity stable than there are forces working to oppose an entity while it’s in motion, static friction is larger than kinetic friction. 

Ques. When is it possible for the coefficient of friction to be larger than one? 

Ans. Yes. Because the adhesive forces between the molecules rise when the contact surface is substantially polished, the frictional force increases. In this situation, the friction coefficient will be larger than one. 

SAKSHI KM

I am Sakshi Sharma, I have completed my post-graduation in applied physics. I like to explore in different areas and article writing is one of them. In my articles, I try to present physics in most understanding manner for the readers.

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