1. Pre-AP Physics: Momentum and Impulse

2. Agenda 4/1 – 4/2 1. Introduction to Momentum Mini-Lab 2. Momentum Notes 3. Momentum Practice HW: Finish Momentum Practice Problems

3. Warm Up What does it mean for a sports team to have “momentum”? What is momentum?

4. What are the factors involved with momentum? Materials: golf ball, foam golf ball, ping pong ball, marble Using the materials provided, identify the factors that affect momentum. Using your observations write an equation for momentum.

5. Momentum Mass in motion Represented by the symbol, p Is a vector quantity

6. Momentum equation Momentum = mass velocity p = m v SI unit is kg*m/s

7. Check Your Understanding How can you increase an object’s momentum? An object has a large momentum if either its mass or velocity is large What is the momentum of an object at rest? The momentum of an object at rest is zero.

8. Momentum practice An ostrich with a mass of 146kg is running to the right with a velocity of 17m/s. What is the momentum? 2.5 x 10 3 kg*m/s to the right

9. Momentum practice (write your answers in scientific notation) A 21kg child is riding a 5.9kg bike with a velocity of 4.5m/s to the northwest. What is the total momentum of the child and the bike together? 1.2 x10 2 kg*m/s to the NW

10. Momentum practice What velocity must a car with a mass of 1210kg have in order to have a momentum of 5.6 x 10 4 kg*m/s to the east? 46 m/s to the east

11. Momentum and Force An object with momentum can be stopped if a force is applied against it for a given amount of time. The greater the object’s momentum, the greater the force needed to stop it

12. Momentum and Force (continued) A force acting for a given amount of time will change an object's momentum. If the force acts opposite the object's motion, it slows the object down. If a force acts in the same direction as the object's motion, then the force speeds the object up.

13. Impulse A change in an object’s momentum The physics of collisions is governed by the laws of momentum

14. Impulse-Momentum Theorem Is closely related to Newton’s 2 nd Law of motion Ft = p or Ft = m(v f -v i ) Force x time interval= change in momentum

15. Impulse and Car Crashes Use impulse to explain how air bags keep you safe in a car crash. Ft = m(v f -v i )