A moon orbiting a planet in the solar system has an orbital period of 5.0 x 104 s, and the distance between the center of the moon and the planet is 2.0 x 108 m. What planet is it?

Question

anonymous · Answer

In this question you're aiming to find the mass of this planet so you can use the centripetal force equation and equates it with the gravitational force
$$Fc = m w ^{2} r $$ 
and $$F _{G}= G \frac{ m _{planet} m _{Moon} }{ r ^{2} }$$   where $$G=6.67×10−11$$

and you can find $$w =\frac{ 2\pi }{ T }$$
then you can solve it and find the planet's mass.