1. 6.1 Mometum and Impulse pp. 208 - 214 Mr. Richter

2. Agenda  Warm-Up  Collect Science Fair Notebooks.  Introduction to Momentum  Notes:  Momentum  Impulse  Stopping Distance and Momentum  Force, Time and Impulse

3. Objectives: We Will Be Able To…  Compare the momentum of different moving objects.  Compare the momentum of the same object moving with different velocities.  Identify examples of change in the momentum of an object.  Describe changes in momentum in terms of force and time.

4. Warm-Up:  If you are asked to stop a rolling boulder, what are two things you would want to know about the boulder?  Discuss at your table.

5. Momentum

6.  What does the word momentum mean in everyday life?  In physics, it means something similar.  Momentum is a measure of how difficult an object would be to stop.  Momentum depends on the mass of the object and its velocity.

7. Momentum  Which has more momentum, a bowling ball or a golf ball?  Actually, it depends which has more speed.  Can you think of a small object that typically has a lot of momentum?  What about a big object that has very little momentum?

8. Calculate Momentum  A 2250 kg pickup truck has a velocity of 25 m/s to the east. What is the momentum of the truck?  p = 56000 kg*m/s

9. Change in Momentum

10.  To cause a change in momentum, a force needs to be applied over a period of time.  A change in momentum is also called impulse.

11. Change in Momentum Calculations  A 1400 kg car moving westward with a velocity of 14 m/s collides with a utility pole and is brought to rest in 0.30 s. Find the magnitude of the force exerted on the car during the collision.  F = 70000 N to the east

12. Change in Momentum  A small amount of force will require a larger amount of time to change momentum.  Tapping on the brakes.  Using airbag.  A large force must be used if the momentum will be changed quickly.  Slamming on the brakes.  No airbag.  A force applied for a longer amount of time will cause a greater change in momentum.  Following through, like in sports.

13. Momentum and Stopping Distance  The more momentum an object has, the harder it is to stop.  This means that objects with more momentum will take longer times and distances to stop.  Using the one-dimensional motion equations from Chapter 2 (p. 58), we can calculate these distances.

14. Momentum and Stopping Distances  A 2250 kg car traveling to the west slows down uniformly from 20.0 m/s to 5.00 m/s. How long does it take the car to decelerate if the force on the car is 8450 N to the east? How far does the car travel during the deceleration?  Δ t= 4.00 s  Δ x= -50.0 m (50 m to the west)

15. Wrap-Up: Did we meet our objectives?  Compare the momentum of different moving objects.  Compare the momentum of the same object moving with different velocities.  Identify examples of change in the momentum of an object.  Describe changes in momentum in terms of force and time.

16. Homework  p. 209 #1-3 Due Monday  Due Tuesday  p. 211 #1, 3  p. 213 #2