You are at the controls of a particle accelerator, sending a beam of 3.90×107m/s protons (mass m ) at a gas target of an unknown element. Your detector tells you that some protons bounce straight back after a collision with one of the nuclei of the unknown element. All such protons rebound with a speed of 3.60×107m/s . Assume that the initial speed of the target nucleus is negligible and the collision is elastic.
Part A Find the mass of one nucleus of the unknown element. Express your answer in terms of the proton mass m .
Part B What is the speed of the unknown nucleus immediately after such a collision?