NEET Exam Model Paper 7

First we have to find a point where the resultant field due to both is zero.Let the point P be at a distance x from centre of bigger star.
i.e., once the body reaches P, the gravitational pull of attraction due to M takes the lead to make m move towards it automatically as the gravitational pull of attraction due to 16M vanishes i.e., a minimum KE or velocity has to be imparted to m from surface of 16M such that it is just able to overcome the gravitational pull of 16M. By law of conservation of energy
+−

GMm

2a

−

G(16M)m

8a

⇒

1

2

mv2−

GMm

8a

(45)⇒v=

3

2

–––– 5GM

a