A 120-kg tackler moving at 5 m/s meets head-on (and tackles) a 80-kg halfback moving at 5 m/s, after which they couple together.

Question

What will be their mutual speed after the collision?
Hint: use conservation of momentum law for INELASTIC collision.

Answer 1

Mass1(tackler) x V1(tackler) + M2(halfback) x V2(halfback) = (M1 + M2) x V(combined)

or

m1(v1) x m2(v2) = (m1+m2)v
=== solve for v ====

(remember, they are running in opposite directions, one velocity should be in the negative direction)