Physics

Problem

A satellite orbits planet X with a speed

v_X

at a distance

r

from the centre of planet X. Another satellite orbits planet Y at a speed of

v_Y

at a distance

r

from the centre of planet Y. The mass of planet X is

M

and the mass of planet Y is

4M

. What is the ratio of

\frac{v_X}{v_Y}

? A. 0.25 B. 0.5 C. 2.0 D. 4.0