In a certain scattering experiment, protons with mass m arefired with initial kinetic energy K0 (momentum p0) at a targetconsisting of helium atoms (the mass of a helium atom isapproximately 4m). Protons scattered at an angle of 90◦ relative totheir initial direction of motion are measured to have a kineticenergy of Kp = 0.54K0 (corresponding to a momentum of pp). Assumingthat each outgoing proton collided with one and only one heliumatom, is this collision elastic, or has the helium atom increasedits internal energy during the collision (it is very hard toincrease the internal energy of a proton)? Follow the stepsoutlined below in order to answer this question. a. (2 points) Drawa useful before and after picture and label it with appropriatesymbols. b. (2 points) Find the momentum of the proton, pp, afterthe collision relative to the momentum of the proton, p0, beforethe collision. c. (3 points) Use a conservation law to determinethe components of the helium atom’s momentum, ~pH, after thecollision in terms of p0. d. (3 points) Use a conservation law andcorrect algebra to answer the question posed.
