The escape velocity of a body on the earth surface is 11.2 km/s. If the same body is projected upward with velocity 22.4 km/s, the velocity of this body at infinite distance from the centre of the earth will be:

A $11.2\sqrt2$ km/s

B Zero

C 11.2 km/s

D $11.2\sqrt3$ km/s

The answer is D.

Solution

$V_\infty=\sqrt{V^2-V_e^2}$. Given $V=2V_e$. $V_\infty=\sqrt{(2V_e)^2-V_e^2}=\sqrt{3}V_e=11.2\sqrt3$ km/s.

Concept Escape velocity and velocity at infinity

66 questions from this chapter have appeared across 26 exam years.