A pair of stars rotates about a common center of mass

PHYSICS · Single correct · AP · Physics 1: Algebra-based · Force and Translational Dynamics · Force and Translational Dynamics

Problem

A pair of stars rotates about a common center of mass. One of the stars has a mass

M

and the other has mass

m

such that

M=2m

. The distance between the centres of the stars is

d

(

d

being large compared to the size of either star). The ratio of kinetic energies of the two stars (

K_m/K_M

) is (A) 1 (B) 2 (C) 4 (D) 9