A 156 gram 8 ball rolls across a pool table at 2 m/s when it collides with a 7 ball of equal mass rolling in the opposite direction at 1.5 m/s. The 8 ball bounces backwards at 1 m/s. Find the momentum of the 7 ball.
v1→, v2 ←, u1 ←.
m1v1 - m2v2 = - m1u1 +p2
p2 = m1•v1-m2•v2 + m1•u1=
= m•(v1- v2 + u1) =
=0.156 (2-1.5+1) = 0.156•15 =0.234 m/s →