Applied Mechanics - Engineering

Q1:

Kinetic friction may be defined as

A friction force acting when the body is just about to move

B friction force acting when the body is in motion

C angle between normal reaction and resultant of normal reaction and limiting friction

D ratio of limiting friction and normal reaction.

ANS:B - friction force acting when the body is in motion

Kinetic friction may be defined as the friction force acting when the body is in motion. When an object is already in motion and is sliding over a surface, the friction force that opposes its motion is referred to as kinetic friction. This friction force arises due to the interactions between the surfaces of the object and the surface it's sliding on. Kinetic friction acts in the direction opposite to the direction of motion and is responsible for slowing down or stopping the object's motion. Therefore, the correct definition of kinetic friction is: friction force acting when the body is in motion.