Question

A circular disc is rotating about its own axis, the direction of its angular momentum is:

• A. radial
• B. along the axis of rotation
• C. along the tangent
• D. perpendicular to the direction of angular velocity

Answer 1

Answer: (B)

along the axis of rotation

Angular momentum: $\overrightarrow{L}=(\overrightarrow{r}\times \overrightarrow{v})$ is along the axis,
$\therefore$ Angular momentum is along the axis of the rotation because in the above $cross$ $product$ it is very clear that direction of angular momentum will be perpendicular to direction of both position vector and velocity vector.