Question

Two bodies of masses m and 4 m are placed at a distance r. The gravitational potential at a point on the line joining them where the gravitational field is zero is : [aieee-2011 4gm

Answer 1

A)

Let the point be the position when the gravitational field is zero

Gmx2=G(4m)(r−x)2

1x=2(r−x)

r−x=2x

x=r3

the point P is at a distance r3 from mass m and 2r3 from mass 4m

V=−GMr3−G(4m)2r3

=−9GMr

Hence d is the correct answer.

Answer 2

Explanation:

A)

Let the point be the position when the gravitational field is zero

Gmx2=G(4m)(r−x)2

1x=2(r−x)

r−x=2x

x=r3

the point P is at a distance r3 from mass m and 2r3 from mass 4m

V=−GMr3−G(4m)2r3

=−9GMr

Hence d is the correct answer.