Friction Formula

Introduction to Friction

Friction is that force which opposes the relative movement of two surfaces in contact. It influences everything from the simple act of walking to driving-thus a very integral part of everyday life.

Formula 

Friction formula is represented as

The values are, the force of friction is Ff, the coefficient of friction is μ and the strength of the normal force is Fn.

The Normal force is equal to the weight of the given body. Thus the Normal force (Fn) can be expressed as:

 

Where,

The mass of the object is m and g is gravity.

The friction formula is for calculating friction between any two given bodies.

Friction Solved Examples

Given below are problems on friction that helps to know where the formula can be used:

Problem 1: A boy is pulling a box of mass 10 Kg. What is the standard force acting and also calculate the frictional force if the coefficient of friction μ is 0.3?

Solution

Given,

Mass, m = 10 Kg,

Normal force, Fn =?

Normal force is given by 

= 10 Kg × 9.8

= 98 N.

Frictional force is presented as

= 0.3 × 98 N.

= 29.4 N.

Problem 2: Nancy of mass 40 Kg is slipping on the frost. If the coefficient of friction acting is 0.45. Calculate the frictional force acting between her and the frost layer?

Answer: 

Given,

Mass m = 40 Kg,

Coefficient of friction μ = 0.3,

The Normal force is presented as Fn = mg

= 40 Kg × 9.8

= 392 N.

The Frictional force is given as 

= 0.45 × 392 N

= 176.4 N.

 

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