Assertion (A): A wheel moving down a perfectly frictionless inclined plane will undergo slipping (not rolling).
Reason (R): For pure rolling, work done against frictional force is zero.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A) is true; friction provides the torque for rolling. Without friction, the wheel slips. Reason (R) is true; in pure rolling, the contact point is stationary, so static friction does no work. However, (R) does not explain (A).
A disc is rolling the velocity of its centre of mass is $v_{\text{cm}}$ then which one will be correct:
(2001)
1. The velocity of highest point is $2 v_{\text{cm}}$ and point of contact is zero
2. The velocity of highest point is $v_{\text{cm}}$ and point of contact is $v_{\text{cm}}$
3. The velocity of highest point is $2 v_{\text{cm}}$ and point of contact is $v_{\text{cm}}$
4. The velocity of highest point is $2 v_{\text{cm}}$ and point of contact is $2 v_{\text{cm}}$
View Answer
For pure rolling, the velocity of the topmost point is $$v*{\text{cm}} + \omega R = 2v_{\text{cm}}$$ and the point of contact is $$v_{\text{cm}} - \omega R = 0$$.