P-1 Gravitation — Science STD 10 — Question

Gravitational potential energy of a body of mass m = $-\frac{G M m}{R+h}$, where G = gravitational constant, M = mass of the earth, R = radius of the earth, h = height of the body from the surface of the earth.

[Note : As the body is bound to the earth due to the earth ’s gravitational froce, the gravitational potential energy of the body is negative. If the body is given kinetic energy equal to $\frac{G M m}{R+h}$ the body will overcome the earth ’s gravitational force. It will then move to infinity and come to rest there.]

Question 27.
What is escape Velocity?
(OR)
Define escape velocity.
Answer:
When a body is thrown vertically upward from the surface of the earth, the minimum initial velocity of the body for which the body is able to overcome the downward pull by the earth and can escape the earth forever is called the escape velocity.