A hockey puck of mass m1 = 2 kg slides at vi = 15 m/s due East. It bumps into a stationary brick of mass m2 = 5 kg. Afterwards, the puck slides away to the northeast with velocity v1f = 10 m/s at θ1 = 30 degrees, and the brick slides to the southeast at v2f at θ2.
Which of the following is the final velocity of the brick?
Is this an elastic collision? That is, does it conserve kinetic energy?