Question

Does frictional force aid or oppose in rotational motion. Pick out the correct statement

• A. It aids motion in translatory motion
• B. It opposes motion in rotation
• C. It aids motion in pure rolling and pure sliding
• D. It aids motion in pure rolling and oppose in pure sliding

Answer 1

The correct option is D It aids motion in pure rolling and oppose in pure sliding

The frictional force opposes the force down the slope thus reducing the linear acceleration so that the linear speed down the slope is not as great as it would have been without the frictional force.

The frictional force provides a torque about the centre of mass of the ball which produces an angular acceleration of the ball and increases its angular speed.

Hence it aids motion in pure rolling and oppose in pure sliding