Two bodies of masses 4m and 9m are seprated by a distance 'r'. The gravitational potential at a point on this line joining them where the gravitational field becomes zero is

Options

A. (-4Gm / r)
B. (-25Gm/r)
C. (-9Gm / r)
D. ( - 13Gm/ r)

Answer

B

Explanation

Answer(2) Let the point be at x distance from 4m, and at (r-x) distance from 9m.
`(4Gm)/x^2 = (G(9m))/(r-x)^2` .
`Rightarrow x = 9r/5` .
let the point P is at a distance of 2r/5 from mass 4m and at (r - 2r/3) from mass 9m. .
`v approx -4Gm/(2r/5) - G(9m)/(r-2r/5)`.
`therefore v = -25Gm/r`.