Dynamics and Equilibrium - Physics Learning 5

Define coefficient of friction

Answer: It is the ratio between the force of limiting friction and the normal reaction. The value of this ratio is constant. Hence, it is called coefficient of friction.

How does force of friction help in walking?

Answer: The force of friction is the necessary force which helps us to walk on ground. The friction is generated between the shoes and the road. We press the ground and as a reaction the ground pushes us forward. The force of friction between sole and ground provides the necessary grip which pushes us forward.

Why is rolling friction extremely small than sliding friction?

Answer: In rolling friction, the wheel is in contact with the ground on a single point hence the wheel rolls without rupturing the cold welds. This is the reason why the rolling friction is much less than the sliding friction.