NEET Physics Question - Rotational Motion - Rolling on Inclined Plane

Assertion (A): If a sphere starts pure rolling down a rough incline plane, work done by friction is zero.

Reason (R): Work done by friction for translational motion is negative and work done by friction for rotational motion is positive and equal in magnitude.

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:

In pure rolling, the point of contact is instantaneously at rest, so static friction does no work (A is true).

Friction opposes translational motion (negative work) and causes rotation (positive work); these works are equal in magnitude, leading to zero net work (R is true and correctly explains A).

Rankers Physics

Work Done by Friction in Pure Rolling

Solution:

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