Question

A particle of mass $m$ is moving in a plane along a circular path of radius $r$. Its angular momentum about the axis of rotation is $L$. The centripetal force acting on the particle is:

• A. $L^2/mr$
• B. $L^{2}m/r$
• C. $L^2/m{r}^3$
• D. $L^2/m{r}^2$

Answer 1

Answer: (C)

$L^2/m{r}^3$

$L=mvr$ $\Rightarrow v=\frac{L}{mr}$
Centripetal force: $\frac{m{v}^2}{r}=\frac{m(\frac{L}{mr}{)}^2}{r}=\frac{L^2}{m{r}^3}$