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
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