Question

A particle is thrown vertically upwards with velocity 11.2 km s^-1 from the surface of earth. Calculate its velocity at height 3R, where R is the radius of earth.

(a) ≈ 9.25 km s^-1

(b) ≈ 5.6 km s^-1

(c) ≈ 11.2 km s^-1

(d) ≈ 4.3 km s^-1

Answer 1

Correct option (b) ≈ 5.6 km s^-1

Explanation :

Let a particle of mass m is thrown vertically upwards with velocity v. Let its velocity be v' at a height 3R from the surface of the earth.

According to the conservation of energy,