posted by marcos .
Suppose all the people of the Earth go to the North Pole and, on a signal, all jump straight up. Estimate the recoil speed of the Earth. The mass of the Earth is 6 1024 kg, and there are about 6 billion people (6 109). Take the average mass of a person to be 74 kg and the distance the average person's center of mass rises after leaving the ground to be 0.2 m.