Q111 / 200 · NEET 2010 (Screening) · Physics
A particle of mass $M$ is situated at the centre of a spherical shell of same mass and radius a. The gravitational potential at a point situated at a/ 2 distance from the centre, will be
- Correct answerA$-\frac{3 G M}{a}$
- B$-\frac{2 \mathrm{GM}}{\mathrm{a}}$
- C$-\frac{\mathrm{GM}}{\mathrm{a}}$
- D$-\frac{4 \mathrm{GM}}{\mathrm{a}}$
Solution
Gravitational potential at point a/2 distance from centre
$$
\begin{aligned}
& =-\frac{\mathrm{GM}}{\mathrm{a}}-\frac{\mathrm{GM}}{\mathrm{a} / 2} \\
& =-\frac{3 \mathrm{GM}}{\mathrm{a}}
\end{aligned}
$$
Hence, the correct answer is option: 'A'.