A planet of mass is in a circular orbit of radius around a star

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

A planet of mass

m

is in a circular orbit of radius

R

around a star. The orbital speed of the planet is

v

. A second planet of mass

2m

is in a circular orbit of radius

1.5R

around the same star. What is the orbital speed of the second planet? (A)

\sqrt{\frac{2}{3}}v

(B)

\sqrt{2}v

(C)

\sqrt{3}v

(D)

2v