1. More Momentum Problems
including 2-D momentum

2. Momentum is a vector quantity.
In two dimensions, the x and y components of momentum are conserved separately.
x direction:
m1v1ix + m2v2ix = m1v1fx + m2v2fx
y direction:
m1v1iy + m2v2iy = m1v1fy + m2v2fy

3. To get final velocities…
Add x- and y-components vectorially. Of course!

4. Skating pair
A 50.0kg skater is traveling due east at a speed of 3.00 m/s. A 70.0kg skater is moving due south at a speed of 7.00 m/s. They collide and hold on to each other after the collision, managing to move off at an angle of θ south of east, with a speed vf. Find θ and vf assuming friction can be ignored.

5. A golf ball
A golf ball strikes a hard, smooth floor at an angle of 30o and rebounds at the same angle. The mass of the ball is 0.047kg and its speed is 45 m/s just before and after striking the floor. What is the impulse applied to the golf ball by the floor?
If the golf ball is in contact with the floor for 10ms, what is the average force that the ball applies on the floor?

6. Crazy fisherman
After an exhausting day of fishing, a man is too tired to walk from his hole in the lake to the shore. He sits on a sled (frictionless) and pulls out a machine gun and fires 100 bullets horizontally all in the same direction.
If the mass of a single bullet is 12.5g and its velocity is 800. m/s, what is the momentum of a single bullet?
If the total mass of the man, sled, and machine gun is 100. kg, what is his velocity after firing the bullets?

7. Continued…
The man slides along for a while and then suddenly collides with a 400kg moose, which was standing still on the ice. After the collision, the moose slides away at an angle of 30o while the man (still on his sled and with his gun) ends up traveling at a 90o angle to his original path.
What is the final speed of the moose?
What is the final speed of the man?
Was the collision elastic? Justify your answer.

8. Fireworks v1 v2
30o
60o
A fireworks rocket is moving at a speed of 50.0m/s. The rocket suddenly breaks into two pieces of equal mass. They fly off with velocities v1 and v2 as shown. What are the magnitudes of v1 and v2?