1. In a particel accelerator, protons are fired at a stationary target and collide elastically with the nuclei of the atoms in the target. In one such experiment, a beam of protons is fired with a speed of 2.10 x 10^7 m/s. the protons that undergo a collision rebound with a speed of 1.68 x 10^7 m/s. what is the mass of the nuclei that the protons are colliding against?
2. A ping-pong ball originally at rest is hit head-on by a bowling ball moving with initial speed vo. It is given that the mass of the ping-pong ball is as good as negligible in comparison with the mass of the bowling ball. What is the speed of the ping pong ball after this elastic collision?