Q. Two small and heavy spheres, each of mass $M$, are placed a distance $r$ apart on a horizontal surface. The gravitational potential at the mid-point on the line joining the centre of the spheres is
A) Zero
B) $- \frac{GM}{r}$
C) $- \frac{2GM}{r}$
D) $- \frac{4GM}{r}$
Explanation
(d) [image:8_image77.emf]
Gravitational potential of $A$ at $O = - \frac{GM}{r/2} = - \frac{2GM}{r}$
For $B$, potential at $O = - \frac{GM}{r/2} = - \frac{2GM}{r}$
$\therefore$ Total potential $= - \frac{4GM}{r}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.