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 = 8 m/s at θ1 = 10 degrees, and the brick slides to the southeast at v2f at θ2 = 11 degrees,
Which of the following is the final speed of the brick?
Is this an elastic collision? That is, does it conserve kinetic energy?