1. Do Now: First, we recognize that we begin with a momentum of zero!
1. A stationary 2000 kg cannon fires a 25kg cannonball horizontally with a speed of 250 m/s. Find the velocity of the cannon after firing the cannonball. Assume friction is negligible.

2. Aim: How can we apply conservation of momentum to head on collisions?
HW:

3. Envelope Activity
Answer the following 2 questions as a group with your partners.
Both questions deal with explosion/recoil.

4. A hunting rifle fires a bullet of mass 0
A hunting rifle fires a bullet of mass kg with a velocity of 500 m/s to the right. The rifle has a mass of 4 kg. Calculate the recoil speed of the rifle as the bullet leaves the rifle.
A 62.1-kg male ice skater is facing a 42.8-kg female ice skater. They are at rest on the ice. They push off each other and move in opposite directions. The female skater moves backwards with a speed of 3.11 m/s. Determine the speed of the male skater.

5. What are the types of collisions we have examined?
Elastic and Inelastic
Up to this point, we have only solved for collisions where one object moves initially.
How is momentum conserved between two cars in a head on collision?
Hopefully you don’t know from experience…

6. Station Activity
The following questions represent head on collisions. Answer them with your partners.

7. Station 1
A 900kg car traveling west at 20 m/s collides head on with a 1,000kg car traveling east. Immediately after the collisions the cars come to rest.
Determine the initial speed of the 1,000kg car.

8. Station 2
A 850kg car traveling north at 15 m/s collides with a 2,000kg car traveling south. After the collision the 850kg car rolls south at 4 m/s. The 2,000kg car come to rest.
Determine the initial speed of the 2,000kg car.

9. Station 3
A 2,000kg truck traveling at 30m/s east collides with a 10,000kg bus traveling west. The vehicles lock at move together at 7 meters per second west.
Calculate the initial speed of the bus.

10. Summary How is an elastic collision different from an inelastic one?
Describe how momentum is conserved for a rifle being fired. What’s important regarding the velocity?