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:
- 5GmM6R
- 2GmM3R
- GmM2R
- GmM3R
Answer
(1) 5GmM6R
Solution
Energy on the surface (at rest): E1 = - GMmR
Orbit radius r = R + 2R = 3R; total energy in orbit: E2 = - GMm2r = - GMm6R
Minimum energy required:
E = E2 - E1
= - GMm6R + GMmR
= 5GmM6R
Answer: (1)