Question 6 - 2021 (17 Mar Shift 1)

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 $\omega$. The angular momentum of M about point A is $L_A$ which lies in the positive $z$ direction and the angular momentum of M about B is $L_B$. The correct statement for this system is:

(1) $L_A$ and $L_B$ are both constant in magnitude and direction

(2) $L_B$ is constant in direction with varying magnitude

(3) $L_B$ is constant, both in magnitude and direction

(4) $L_A$ is constant, both in magnitude and direction