Kinetic Friction - Practice Questions & MCQ

1. Kinetic friction occurs when there is relative motion between two bodies that are in contact.

2. When two bodies slip over each other, the force of friction is called kinetic friction.

3. It is a constant friction force, i.e, it does not depend upon the speed of relative motion.

4. The magnitude of the kinetic friction is proportional to the normal force acting between the two bodies.

5. It is denoted by:- 

$\begin{aligned} & f_K \alpha N \\ & f_K=\mu_K N \\ & f_K=\text { kinetic friction } \\ & \mu_K=\text { coefficient of kinetic friction is constant } \\ & N=\text { reaction } \\ & \text { Coefficient of friction }\left(\mu_k\right)\end{aligned}$

• It is unitless and dimensionless.
• It depends on the nature and material of the two bodies in contact.
• It doesn't depend on the speed of the sliding bodies.