Q.

Initially a satellite of 100 kg is in a circular orbit of radius 1.5RE . This satellite can be moved to a circular orbit of radius 3RE  by supplying α×106 J of energy. The value of α is______. 

(Take Radius of Earth RE=6×106m and  𝑔=10m/s2)        [2026]

1 100  
2 500  
3 1000  
4 150  

Ans.

(3)

Energy of a satellite in a circular orbit is given as

E=-GMEm2r ;  r=radius of circular orbit

Required energy to be supplied=ΔE=Ef-Ei

ΔE=(-GMEm2(3RE))-(-GMEm2(1.5RE))

       =GMEm6RE

Now,  g=GMERE2GMERE=gRE

  ΔE=16gmRE

                 =16×10×100×6×106

                  =1000×106

α=1000