Q.

A satellite of mass m is orbiting the earth (of radius R) at a height h from its surface. The total energy of the satellite in terms of g0, the value of acceleration due to gravity at the earth’s surface, is                  [2016]
 

1 mg0R22(R+h)  
2 -mg0R22(R+h)  
3 2mg0R2R+h  
4 -2mg0R2R+h  

Ans.

(2)

Total energy of satellite at height h from the earth's surface,

        E=PE+KE=-GMm(R+h)+12mv2                             ...(i)

Also, mv2(R+h)=GMm(R+h)2

or,    v2=GMR+h                                                                     ...(ii)

From eqns. (i) and (ii),

      E=-GMm(R+h)+12GMm(R+h)=-12GMm(R+h)

          =-12GMR2×mR2(R+h)=-mg0R22(R+h)