1. Conservation Collisions

2. Conservation of Linear Momentum The change in momentum of a system is equal to the impulse put on the system.

3. Conservation of Linear Momentum For example: Jeff Bagwell hits a baseball… Initially

4. Conservation of Linear Momentum For example: Jeff Bagwell hits a baseball… During hit

5. Conservation of Linear Momentum For example: Jeff Bagwell hits a baseball… Finally

6. Two types of collisions Elastic: The objects do not stick together or change shape. Momentum and kinetic energy are conserved. Inelastic: The objects do stick together and/or change shape. Only momentum is conserved!

7. Example of an elastic collision The cue ball hits two billiard balls initially at rest on a billiard table. Assume that the cue ball stops after hitting the other balls. What is the final velocity of the red and blue ball? y θ x

8. y θ x

9. y θ x

10. y θ x We have three equations and four unknowns. We cannot solve this problem without more information. You will usually be given the speed or angle of one of the balls.

11. Example of an inelastic collision A pieces of putty is thrown against a box sitting at rest on a frictionless table. If the putty is twice the mass of the box, what is the speed of the box/putty combination compared to the original speed of the putty?

12. Impulse and Momentum The total impulse acting on a systems is ALWAYS equal to the change in its momentum x-component Momentum Impulse

13. Impulse and Momentum During collisions momentum is always conserved and kinetic energy is sometimes conserved Inelastic Collisions Elastic Collisions

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