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Gravitation

Question
CBSEENPH11026261

A launching vehicle carrying an artificial satellite of mass m is set for launch on the surface of the earth of mass M and radius R. If the satellite is intended to move in a circular orbit of radius 7R, the minimum energy required to be spent by the launching vehicle on the satellite is (Gravitational constant= G)

  • GMmR

  • - 13 G M m14 R

  • GMm7R

  • -G M m14 R

Solution

B.

- 13 G M m14 R

The energy of artificial satellite at the surface of the earth

    E1 =  - G M mR

When the satellite is intended to move in a circular orbit of radius 7R, then energy of artificial satellite

   E2- 12G M m7R

The minimum energy required

    E = E1 - E2   

   = - G M mR  + 12 G M m7R

     = - 14 G M m + G  M m14 R

E   = -13 G M m14R