Conservation of Momentum Momentum in a Closed Isolated

Conservation of Momentum

Momentum in a Closed, Isolated System • A system which does not gain or lose mass is said to be a closed system. • When the net external force on a closed system is zero, the system is described as an isolated system.

Momentum in a Closed, Isolated System • The law of conservation of momentum states that the momentum of any closed, isolated system does not change. Law of Conservation of Momentum pf = pi

Conserved n n Total momentum of a system before and after an interaction remains constant Momentum before = Momentum After ‘ notation is used to designate after m 1 v 1 + m 2 v 2 = m 1 v 1 ’ + m 2 v 2 ’

Example 1 n 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?

Example 2 n Calculate the recoil velocity of a 5. 0 kg rifle that shoots a. 050 kg bullet at a speed of 120 m/s.

Example 3 n A 3. 0 kg cart traveling at. 50 m/s has a 2. 0 kg mass dropped on it. What is its new velocity?

Example 4 n 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?

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