## College Physics (4th Edition)

The correct answer is: (a) Earth moves away from the spaceship at $0.60~c$
In general, if object A moves away from object B at a speed $v$ according to observers on object B, then object B moves away from object A at a speed $v$ according to observers on object A, The correct answer is: (a) Earth moves away from the spaceship at $0.60~c$