Q.
Two bodies of masses m and 9m are placed at a distance r. The gravitational potential at a point on the line joining them, where gravitational field is zero, is ( G is universal gravitational constant)
Mass of first body (m1)=m
Mass of second body (m2)=9m
Distance between the bodies (d)=r
Now, distance of the point from the body of mass m,
where gravitational field is zero is given by x=m1m2+1d
or, x=m9m+1r or, x=4r
Now, (r−x)=r−4r=43r ∴ Potential, v=v1+v2 =−xGm1−(r−x)Gm2 =−r/4Gm−3r/4G(9m) =−r4Gm−r12Gm =−r16Gm