A 110-kg tackler moving at 2.5m/s meets head-on (and holds on to) an 82-kg halfback moving at 5.0m/s. What will be their mutual speed immediately after the collision?

Answer 1

conserve momentum --
110*2.5 + 0*82(-5) = (110+82)v
Now solve for v

Answer 2

Given: M1 = 110kg, V1 = 2.5m/s.
M2 = 82kg, V2 = -5m/s(left).

M1*V1+M2*V2 = M*1*V+M2*V
110*2.5+82*(-5) = 110V+82V
275-410 = 192V
-135 = 192V
V = -0.70m/s(left).