Two balls of mass 0.6 kg and 0.8 kg are connected by a low-mass spring. This device is thrown through the air with low speed, so air resistance is negligible. The motion is complicated: the balls whirl around each other, and at the same time the system vibrates, with continually changing stretch of the spring. At a particular instant, the 0.6 kg ball has a velocity ‹ 5, ?6, 2 › m/s and the 0.8 kg ball has a velocity ‹ 4, 3, 5 › m/s.
(a) At this instant, what is the total momentum of the device?
(b) What is the net gravitational (vector) force exerted by the Earth on the device?
(c) At a time 0.05 seconds later, what is the total momentum of the device?