Q.

A spaceship of mass 2×104 kg is launched into a circular orbit close to the Earth’s surface. The additional velocity to be imparted to the spaceship in the orbit to overcome the gravitational pull will be (if g=10 m/s2 and radius of Earth = 6400 km)                  [2023]

1 11.2(2-1) km/s  
2 7.9(2-1) km/s  
3 8(2-1) km/s  
4 7.4(2-1) km/s  

Ans.

(3)

vorbit=GMR=gR

vescape=2GMR=2gR

Δv=(2-1)gR=8(2-1) km/s