1. An experiment is performd in a physics laboratory to find the mass of a stationary particle, B. A proton, A, of mass 1.7 x 10^-27 kg, travelling at 4.0 x 10^6 m/s, strike B and bounces straight back at a speed of 2.0 x 10^6 m/s. If B moves ahead at 1.0 x 10^6 m/s. calculate B's mass 2. Two, studends, C and D, are facing each other on "friction-less" roller skates. C has a mass of 80kg and D has a mass of 50kg. Now they push each other and D acquires a velocity of 4.4m/s [W]. What velocity does C acquire?