Two satellites of earth `S_(1)` and `S_(2)` are moving in the same orbit. The mass of `S_(1)` is four times the mass of `S_(2)`. Which one of the following statements is true?

Options

A. The time period of `S_(1)` is four times that of `S_(2)`
B. The potential energies of earth and satellite in the two cases are equal
C. `S_(1)` and `S_(2)` are moving with the speed
D. The kinetic energies of the two satellites are equal

Answer

C

Explanation

In the same orbit, orbital speed of satellites remain same. When two satellite earth are moving in the same orbit, then time periods of both are equal.
From Kepler's third law
`T^(2) prop r^(3)`
Time period is independent of mass, hence their time periods will be equal. The potential energy and kinetic energy are mass dependent, hence the PE and KE of satellites are not equal.
But, if they are orbiting in the same orbit, then they have equal orbital speed.