A billiard ball of mass m hits another one of the same mass. The first ball moves off at 30 degrees. For an elastic collision what are the velocities of both balls after the collision. In the lab frame where the second ball starts at rest, what angle compared to the direction of initial velocity of the first ball does the 2nd ball move?

An electron moves with a constant horizontal velocity of 3.0 × 106 m/s and no initial vertical velocity as it enters a deflector inside a tv tube. the electron strikes the screen after traveling 26 cm horizontally and 19 cm vertically upward with no horizontal acceleration. what is the constant vertical acceleration provided by the deflector? (the effects of gravity can be ignored.)