Question

Each of five satellites makes a circular orbit about an object that is much more massive than any of the satellites. The mass and orbital radius of each satellite are given below. Which satellite has the greatest speed?

	Mas	Radius
(A)	½m	R
(B)	m	1/2R
(C)	m	R
(D)	m	2R
(E)	2m	R

Answer 1

Correct option  (B) m ½R

Orbital speed is found from setting GMm/r² = mv²/r which gives v = (GM/r) where M is the object being orbited. Notice that satellite mass does not affect orbital speed. The smallest radius of orbit will be the fastest satellite.