Two small and heavy sheres, each of mass M, are placed at a distance r apart on a horizontal surface. The gravitational potential at the midpoint on the line joining the centre of the spheres is:

Options

A. zero
B. `-(GM)/(r)`
C. `-(2GM)/(r)`
D. `-(4GM)/(r)`

Answer

D

Explanation

Gravitational potential at O due to mass M at A = `-(GM)/(r//2)=-(2GM)/(r)`

Gravitational potential at O due to mass M at `B=-(GM)/(r//2)=-(2GM)/(r)`
`therefore` Total gravitational potential at `O=-(4GM)/(r)`