1. Conservation of Momentum Momentum before interaction = Momentum after interaction

2. Momentum Rocket = Momentum Exhaust A huge 20-kg rocket zooms upward at 5 meter/second. At the same exact time, 10-kg of water shoots downward. How fast does the water shoot out?

3. Momentum Rocket = Momentum Exhaust mv = mv 20 x 5 = 10 x ??? 100 = 10 x ???

4. Momentum Rocket = Momentum Exhaust mv = mv 20 x 5 = 10 x ??? 100 = 10 x 10 m/s

5. A toy 10-kg fire truck is rolling at 10 m/s when it hits a parked 5-kg toy car… mv 10 x 10 mv 5 x 0

6. After the collision, the car rolls at 4 m/s. What is the velocity of the fire truck? mv 10 x ? mv 5 x 4

7. mv = mv + mv 10 x 10 = 10v + (5 x 4) 100 = 10v + 20 -20 80 = 10v 10 10 v = 8 m/s

8. A blue 10- kg box car rolls at 6 m/s and crashes into a 20-kg box car that is at rest. 10 kg 6 m/s 20 kg 0 m/s

9. A blue 10- kg box car rolls at 6 m/s and crashes into a 20-kg box car that is at rest. 10 kg 6 m/s 20 kg 0 m/s 10 kg20 kg ? m/s After the crash, both cars are stuck together. What is their velocity?

10. 10 kg20 kg ? m/s After the crash, both cars are stuck together. What is their velocity? mv + mv = mv (10x6) + (20x0) = 30V 60 = 30V V= 2 m/s

11. Law of Independence of Motion: Gravity doesn’t care if an object is moving horizontally or vertically, it will still cause it to fall at 9.8 m/s 2. For example, if I threw a rock off of a cliff and my friend just dropped another rock at the same time, both rocks would hit the water at the same time (one would just land farther away from the cliff).