Question

The potential energy of a two particle system separated by a distance $r$ is given by $U\left(r\right)=\frac{A}{r}$, where $A$ is a constant. Find the magnitude of radial force $F_r,$ that each particle exerts on the other.

• A. $\frac{A}{r^2}$
• B. $\frac{A}{r}$
• C. $A{r}^2$
• D. $Ar$

Answer 1

The correct option is A $\frac{A}{r^2}$

The radial force is related to the potential energy as
$F=-\frac{dU}{dr}=-\frac{d}{dr}\left(\frac{A}{r}\right)=\frac{A}{r^2}$

$|F|=\frac{A}{r^2}$
Option A is correct.