When a particle is moving in a circular path around a fixed point in a plane,the direction of its angular momentum is ........

$A$ particle moves along a circular path with decreasing speed. Hence,

$A$ mass $m$ is moving with a constant velocity $v$ along a line parallel to the $X$-axis. Its angular momentum with respect to the origin or the $Z$-axis is:

$A$ point mass $m$ is attached to one end of a string passing through a cylindrical tube. The string is held in hand,and the point mass moves in a horizontal circle of radius $r_1 = 2 \ m$ with a speed of $v_1 = 4 \ m/s$. The string is then pulled down so that the radius is reduced to $r_2 = 1 \ m$. Calculate the new linear velocity,angular velocity,and the ratio of the final kinetic energy to the initial kinetic energy.

When does the magnitude of angular momentum become zero?

$A$ particle is moving along a straight line parallel to $x-$ axis with constant velocity. Its angular momentum about the origin