question_answer 18)

The escape velocity of projectile on the surface of earth is 11-2 km . If a body is projected out with thrice of this speed, find the speed of the body far away from the earth. Ignore the presence of other planets and sun.  

Answer:

Here,  Velocity of projection of the body et w be the mass of the projectile andbe the velocity of the projectile when far away from the earth (i.e., out of gravitational field of earth). Then, from the law of conservation of energy                                     Or