Question

A hockey puck of mass m1, moving with initial speed u, collides with another puck of mass m2, initially at rest. After the collision, the first puck moves with known speed v in the direction perpendicular to the initial. Whats the final speed of the second puck?

Answer 1

unlikely but x momentum before = m1 u1
y momentum before = 0
x momentum after = m2 u2b so u2 b = (m1/m2)u1
y momentum after = m1 v +m2 v2b = 0
so
v2b = - (m1/m2)v so V2b is known if v is known