Question

The angle between the linear momentum and angular momentum of a particle moving along a circle is

• A. $0^{\circ}$
• B. $45^{\circ}$
• C. $90^{\circ}$
• D. $180^{\circ}$

Answer 1

Answer: (C)

$90^{\circ}$

Answer 2

The angular momentum of a particle moving along a circle of radius $r$ is
$\vec{L}=\vec{r}\times\vec{p}$ where $\vec{p}$ is the linear momentum of the particle
By the definition of vector product, $\vec{L}$ is perpendicular to $\vec{p}$.
So the angle between them is $90^{\circ}$.