Q.

The minimum energy required to launch a satellite of mass m from the surface of Earth of mass M and radius R in a circular orbit at an altitude of 2R from the surface of the Earth is               [2024]
 

1 5GmM6R  
2 2GmM3R  
3 GmM2R  
4 GmM3R  

Ans.

(1)

Energy of satellite on surface of earth,

Ei=-GmMR

The energy at distance (2R+R=3R),

Ef=-GMm2(3R)=-GMm6R

Energy required to launch the satellite,

       E=Ef-Ei=-GMm6R-(-GMmR)

                              =5GMm6R