A 2.0 kg mass traveling at 3.0m/s strikes another 2.0kg mass traveling at -1.0m/s. They collide and have a perfectly elastic collision. If the second mass is moving at 3.0m/s after the collision,
what is the speed and direction of the first mass?

Cyclotrons are widely used in nuclear medicine for producing short-lived radioactive isotopes. these cyclotrons typically accelerate h- (the hydride ion, which has one proton and two electrons) to an energy of 5 mev to 20 mev. this ion has a mass very close to that of a proton because the electron mass is negligible—about 1 2000 of the proton’s mass. a typical magnetic field in such cyclotrons is 1.9 t. (a) what is the speed of a 5.0-mev h-? (b) if the h- has energy 5.0 mev and b = 1.9 t, what is the radius of this ion’s circular orbit?