A projectile proton with a speed of 500 m/s collides elastically with a target proton initially at

Question:

A projectile proton with a speed of 500 m/s collides elastically with a target proton initially at rest. The two protons then move along perpendicular paths, with the projectile path at 60' from the original direction. After the collision, what are the speeds of

(a) The target proton and

(b) The projectile proton?