JEE Main · 2021 · 31 Aug 2021 · Shift 1 · Rotational Mechanics

Angular momentum of a single particle moving with constant speed along circular path :

(A)remains same in magnitude but changes in the direction
(B)changes in magnitude but remains same in the direction
(C)remains same in magnitude and direction✓ Correct
(D)is zero

Answer: (C)

Solution

Taken about the centre of the circular path, the angular momentum has magnitude

L = m v r

, which is constant because the speed and the radius do not change. Its direction is along the fixed axis perpendicular to the plane of the motion, so it too stays fixed. The angular momentum remains the same in both magnitude and direction. In the actual examination, this question was awarded bonus marks.

JEE Main · 2021 · 31 Aug 2021 · Shift 1 · Single correct option

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