We know, L=m(r×v)
Now with respect toA, we always get direction
of L along +ve z-axis and also constant magnitude as mvr. But with respect to B, we get constant magnitude but continuously changing direction.
JEE Main 2021 — Physics Mechanics
2021mcqeasy
A mass M hangs on a massless rod of length l which rotates at a constant angular frequency. The mass M moves with steady speed in a circular path of constant radius. Assume that the system is in steady circular motion with constant angular velocity ω. The angular momentum of M about point A is LA which lies in the positive z direction and the angular momentum of M about B is LB. The correct statement for this system is:
Official previous-year question
Held on 17 Mar 2021 · Verified 6 Jul 2026.
Options
- A
LA and LB are both constant in magnitude and direction
- B
LB is constant in direction with varying magnitude
- C
LB is constant, both in magnitude and direction
- D
LA is constant, both in magnitude and direction
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