1. Conservation of Momentum

2. Conserved Total momentum of a system before and after an interaction remains constant Momentum before = Momentum After Two balls collide, the momentum of ball 1 (m 1 v 1 ) and ball 2 (m 2 v 2 ) before the collision is equal to the momentum after ‘ notation is used to designate after m 1 v 1 + m 2 v 2 = m 1 v 1 ’ + m 2 v 2 ’

3. Law Total momentum of an isolated system remains constant This law will not apply if there are forces acting “external” to system If system is a falling rock, momentum of the rock does not seem conserved but its momentum is actually transferred to the earth

4. Example 1 A 10000 kg railroad car traveling 24 m/s strikes an identical car at rest. If the two cars lock together after the collision, what is their speed afterward?

5. Video Example Linear Momentum | Circus Physics

6. Example 2 Calculate the recoil velocity of a 5.0 kg rifle that shoots a.050 kg bullet at a speed of 120 m/s.

7. Example 3 A 3.0 kg cart traveling at.50 m/s has a 2.0 kg mass dropped on it. What is its new velocity?

8. Example 4 A small car of mass (1000 kg) traveling at 20 m/s strikes a 3000 kg truck initially at rest. The car bounces back from the truck with a velocity of 10 m/s, what is the velocity of the truck now?

9. Example 5 A 1000 kg car traveling at 20m/s collides head-on with a 3000kg truck traveling at 20 m/s. After the collision, the truck’s velocity is zero, what is the velocity of the car?