Question

The gravitational potential due to a system of two concentric thin spherical shells of mass $M$ and $2M$ and radius $R$ and $3R$ respectively at the point $P$ is

• A. $-\frac{GM}{R}$
• B. $-\frac{5}{3}\frac{GM}{R}$
• C. $-\frac{3GM}{2R}$
• D. $-\frac{GM}{2R}$

Answer 1

Answer: (B)

$V_{P} = -\frac{G2M}{3R} - \frac{GM}{R}$
$ = - \frac{GM}{R}\left(+\frac{2}{3}+1\right) $
$= -\frac{5}{3} \frac{GM}{R}$