A 4.0-kg meatball is moving with a speed of 6.0 m/s directly toward a 2.0 kg meatball which is at rest. The two meatballs collide and stick together. What is their velocity immediately after the (inelastic) collision?
Since no external forces act on the two-meatball system, the system's momentum is conserved. The system's momentum before the collision is:
pbefore = m1v1 + m2v2 = m1v1
and the system's momentum after the collision is:
pafter = (m1 + m2)v
If momentum is conserved, then:
pafter = pbefore
(m1 + m2)v = m1v1
The velocity of the 6.0-kg meatball immediately after the collision is 4.0 m/s.
This is the "more traditional" solution to the problem.
last update March 21, 2006 by JL Stanbrough