Two identical satellites are moving around the Earth in circular orbits at heights 3R and R respectively where R is the radius of the Earth. The ratio of their kinetic energies is x. Find x.

Options

A. `1:4`
B. `4:1`
C. `1:8`
D. `8:1`

Answer

C

Explanation

Angular momentum `J=mvr`
`J^(2)=m^(2)v^(2)r^(2)`
or `J^(2)/2=(1/2 mv^(2))mr^(2)` or `K.E.=J^(2)/(2mr^(2))`