Question

A satellite of mass M moves in a circular orbit of radius R at a constant speed v. Which of the following must be true? 

I. The net force on the satellite is equal to Mv²/R and is directed toward the center of the orbit. 

II. The net work done on the satellite by gravity in one revolution is zero. 

III. The angular momentum of the satellite is a constant. 

(A) I only 

(B) III only 

(C) I and II only 

(D) II and III only 

(E) I, II, and III 

Answer 1

Correct option (E) I, II, and III

Circular orbit = constant r, combined with constant speed gives constant angular momentum (mvr). As it is a circular orbit, the force is centripetal, points toward the center and is always perpendicular to the displacement of the satellite therefore does no work.