Two artificial satellites I and II have circular orbits of radii R and 2R, respectively, about the same planet. The orbital velocity of satellite I is v. What is the orbital velocity of satellite II?
a) v/2
b) v/sqrt(2)
c) sqrt(2)*v
d)2v

The correct answer is B but I cannot for the life of me figure out how...

Question

Two artificial satellites I and II have circular orbits of radii R and 2R, respectively, about the same planet. The orbital velocity of satellite I is v. What is the orbital velocity of satellite II?
a) v/2
b) v/sqrt(2)
c) sqrt(2)*v
d)2v

The correct answer is B but I cannot for the life of me figure out how...

anonymous · Answer

$$V=\sqrt{GM/R},,,\rightarrow    v/V=\sqrt{2R/R} ,,,V =v/\sqrt{2}$$