1. Momentum

2. Collisions Perfectly inelastic collisions –When two objects stick together and move as one mass Elastic collisions –When two objects return to their original shape and move separately

3. Elastic Collisions The total kinetic energy is conserved. M 1 V 1i + M 2 V 2i = M 1 V 1f + M 2 V 2f

4. Example 27 A 0.015 kg marble moving to the right at 22.5 cm/s makes an elastic head-on collision with a 0.015 kg marble moving to the left at 18.0 cm/s. After the collision, the first marble moves to the left at 18.0 cm/s. A. Find the velocity of the second marble after the collision.

5. Example 28 A 0.015 kg marble moving to the right at 22.5 cm/s makes an elastic head-on collision with a 0.015 kg marble moving to the left at 18.0 cm/s. After the collision, the first marble moves to the left at 18.0 cm/s. B. Verify your answer by calculating the total kinetic energy before and after the collision.

6. Example 29 A 16.0 kg canoe moving to the left at 12 m/s makes an elastic head-on collision with a 4.0 kg raft moving to the right at 6.0 m/s. After the collision, the raft moves to the left at 22.7 m/s. B. Find the velocity of the canoe after the collision.

7. Example 30 A 16.0 kg canoe moving to the left at 12 m/s makes an elastic head-on collision with a 4.0 kg raft moving to the right at 6.0 m/s. After the collision, the raft moves to the left at 22.7 m/s. B. Verify your answer by calculating the total kinetic energy before and after the collision.

8. Inelastic Collisions Most collisions are neither elastic or perfectly inelastic. –They lose some kinetic energy –Deformation takes place –Objects move together for a period of time, then move separately.

9. Example 31 A 82 kg man drops from rest on a diving board 3.0 m above the surface of the water and comes to rest 0.55 s after reaching the water. What force does the water exert on him?