Two bodies of masses \( m \) and \( 4 m \) are placed at a distance \( r \). The gravitational p...

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]
(a) Zero
(b) \( -\frac{4 G m}{r} \)
(c) \( -\frac{6 G m}{r} \)
(d) \( -\frac{9 G m}{r} \)