Question

A disc is rolling on a rough horizontal surface. The instantaneous speed of the point of contact during perfect rolling is zero with respect to ground.
The force of friction can help in achieving pure rolling condition.
A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Answer 1

Correct Answer - B
(b) Velocity of point of contact
`V = (V_(CM) - omega R)`
When purer rolling occurs `V_(CM) = omega R`
Hence `V = 0`
Also frictional force can provide torque which further helps in achieving the pure rolling condition.