A sphere is performing pure rolling on a rough horizontal surface with constant angular velocity.
Assertion (A): Frictional force acting on the sphere is zero.
Reason (R): Velocity of contact point is zero.
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false
Solution:
Assertion (A) is true; if a sphere rolls purely with constant angular velocity, no force (including friction) is needed to maintain its motion. Reason (R) is true; for pure rolling, the contact point is instantaneously at rest. However, R is a definition of pure rolling, not the explanation for zero friction in this specific case (due to zero acceleration).
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