Question

A projectile is projected with velocity kv_e in vertically upward direction from the ground into the space. (v_e is escape velocity and k < 1). If air resistance is considered to be negligible then the maximum height from the centre of earth to which it can go, will be (R = radius of earth)

(a) R/k² +1

(b)R/k² -1

(c) R/1 -  k²

(d)  R/R+1

Answer 1

Correct option (c) R/1- k²

Explanation

From the law of conservation of energy Difference in potential energy between ground and maximum height = Kinetic energy at the point of projection 

By solving height from the surface of earth 

So height from the centre of earth