Two hockey pucks of equal mass (168 g) undergo a glancing collision

Question

Two hockey pucks of equal mass (168 g) undergo a glancing collision. Puck 1 is initially at rest and is struck by puck 2 travelling at a velocity of 13.0 m/s [E]. Puck 1 travels at an angle of 

[E 18 N] after the collision, while puck 2 travels at an angle of [E 4 S]. Determine the final velocity of each puck.

Answer 1

Energy is not conserved in this collision. However, both components of momentum are.

This leads to two equations. (The mass can be take as 1.0 without loss of generality. )

For the East/West component of momentum: 2 = v1 cos(18) + v2 cos(4)

For the North/South component: 0 = v1 sin(18) - v2 sin(4)

(Here v1 and v2 are the final velocities)

This is a set of two linear equations with two unknowns.

The solution is v1 = 0.3725 v2 = 1.650