Question

The period of a satellite moving in circular orbit near the surface of a planet is independent of

• A. mass of the planet
• B. radius of the planet
• C. mass of the satellite
• D. density of planet

Answer 1

Answer: (C)

mass of the satellite

Time period in terms of orbital speed is given by
$T=\frac{2\pi r}{v_o}=\frac{2\pi r}{\sqrt{\frac{GM}{r}}}=2\pi \sqrt{\frac{r^3}{GM}}$
From the above equation, we can see that $T$ depends on radius of the orbit and the mass (density) of the planet but not the mass of the satellite.