Question

Hockey puck B rests on a smooth ice surface and is struck by a second puck A, which has the same mass. Puck A is initially traveling at 14.5 m/s and is deflected 20.0 ∘ from its initial direction. Assume that the collision is perfectly elastic.

Find the final speed of each puck and the direction of B's velocity after the collision.

Answer 1

Through conservation of momentum, I determined that:
\[m _{1}v _{1} + m _{2}v _{2} = m _{1}^{f}v _{1}^{f} +m _{2}^{f}v _{2}^{f}\]

and since all the masses are the same and B starts and rest:
\[v _{1}=v _{1}^{f} +v _{2}^{f}\]

I'm stuck from there.

Answer 2

This question involves motion in two dimensions. You therefore must use trigonometry and analyse the momentum of the objects in each direction independently.