How to calculate Friction Force ? (original) (raw)
Last Updated : 23 Jul, 2025
Friction is a force that acts to slow down the movement of two objects that are in contact. There are two types of friction****:** **Static and Kinetic. When friction is powerful enough to inhibit movement between two objects, it is called **static friction. When the frictional force is insufficient to halt all motion, kinetic friction is applied; heat generation is one of the effects of **kinetic friction.
Friction Formula Physics
**F f = μη
Where,
Ff = force of friction acting on the object
μ = coefficient of friction
η = normal force acting on the object
Solved Examples
**1. A child 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?
Mass, m = 10 Kg,
Normal force is given by Fn = mg
= 10 Kg × 9.8 m/s2
= 98 N.
The Frictional force is articulated by Ff = μ Fn
= 0.3 × 98 N.
= 29.4 N.
**2. Nancy of mass 40 Kg is slipping on the frost. If the coefficient of friction acting is 0.45. Find the frictional force acting between her and the frost layer?
Mass m = 40 Kg
Coefficient of friction μ = 0.45
The Normal force is articulated by Fn = mg
= 40 Kg × 9.8 m/s2
= 392 N.
The Frictional force is articulated by Ff = μ Fn
= 0.45 × 392 N
= 176.4 N.
**3. A force of 100N is applied to a box on the floor with a friction coefficient of 0.2. Calculate the friction force.
The normal force Fn=100 N
Coefficient of friction= 0.2
Friction force (Ff) = μ Fn
= 0.2 x 100
=20 N
**4. A force of 60N is applied to a box that is resting on the floor and has a coefficient of friction of 0.4. Calculate the friction force.
The normal force Fn=60 N
Coefficient of friction= 0.4
Friction force (Ff) = μ Fn
= 0.4 x 60
= 24 N
**5. A boy pulls a body of mass 50Kg resting on a flat horizontal surface. Calculate the frictional force if the coefficient of friction is 0.3.
Mass of the body m = 50Kg
Coefficient of friction =0.3.
The friction formula is given as
Ff = μ × Fn
Here N is the normal force given by the formula
N = m×g
'g' is the acceleration due to gravity = 9.81 m/s2
So , N = 50 × 9.81
= 490.5 Kg m/s2
= 490.5 N
Now substituting the values in the friction formula we get the required frictional force
F = 0.3 × 490.5 N
= 147.15N
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