Frictional Force in Circular Motion – Rankers Physics
Topic: Circular Motion
Subtopic: Uniform Circular Motion

Frictional Force in Circular Motion

Assertion (A): A cyclist is cycling on a rough horizontal circular track with increasing speed. Then the net frictional force on cycle is always directed towards centre of the circular track.
Reason (R): For a particle moving in a circle, component of its acceleration towards centre, that is, centripetal acceleration should exist (except when speed is zero instantaneously).
 
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 false. For increasing speed, friction must provide both a tangential force (for speed increase) and a centripetal force (for circular path). Thus, the net frictional force is not solely towards the center. Reason (R) is true, centripetal acceleration is necessary for circular motion whenever speed is non-zero. Since A is false and R is true, and this specific option is not available, we choose option (4) as the closest available if compelled.

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