1. Name 3 vectors and 3 scalars.
Do Now:
Name 3 vectors and 3 scalars.
A hammer exerts an impulse of 1.5 Newton.seconds on a nail for a time of 3x10-2 seconds. What was the force of the hammer on the nail?
J = Ft = ΔP
F = 50N

2. Aim: How is momentum conserved?
HW:

3. How can we determine Impulse from a graph?
Force vs. time Force (N) Time (seconds)

4. My 1500 kg car accelerates from rest at a red light.
Calculate the impulse acting on the car over the first 5.78 seconds.
Determine the car’s final velocity.

5. Conservation of Momentum
In a system, the momentum of the individual components may change, but the total momentum of the system remains constant.
Law of Conservation of Momentum:
pbefore = pafter (in reference table)
How is this useful?

6. Elastic Collisions Describe how pool balls behave when they collide.
Animation
Two objects collide and SEPARATE without any sticking
When the two objects have the same MASS,
they TRADE MOMENTUM

7. Example #1
A 2 kilogram ball moving at +3 meters per second collides with a 3 kilogram ball at rest.
Assuming that the 2 kilogram ball stops after the collision, calculate the velocity of the 3 kilogram ball after the collision.

8. Inelastic Collision
What would be the opposite of an elastic collision?
Animation
Two objects collide and STICK together
The MASSES of the objects
COMBINE TO FORM A SINGLE MASS

9. Example #2
A 5 kilogram cart moving right at 6 meters per second collides with a 10 kilogram cart moving left at 6 meters per second.
If the two carts stick together during the collision, determine their final velocity.

10. SUMMARY How do we calculate impulse from a graph?
Define the Law of Conservation of Momentum.
Why does the direction of an object’s motion matter?
Name and describe the two situations where momentum is conserved.

11. EXTRA
57. A kg basketball hits a wall head-on with a forward speed of 18.0 m/s. It rebounds with a speed of 13.5 m/s. The contact time is seconds. (a) determine the impulse with the wall, (b) determine the force of the wall on the ball