A billiard ball collides head-on with billiard ball at rest. (a.) Sketch a position vs. time graph for each ball, include position before the collision, once the collision occurs and after the collision. (b.) What can be said about the conservation of momentum for the collision? Explain your answer.

1. Write down the total momentum for two marbles of mass, m, both moving at velocity, v .What is the kinetic energy of the system?
2. When you drop two marbles at once, why doesn't only one marble come off the end twice as fast? Write down the kinetic energy of one marble with mass m and velocity 2v and compare this to your answer in Experiment 1 Post Lab Question 4 to check.

Note: Assume the collisions are perfectly elastic.

Experiment 1: Conservation of momentum

Data Sheet

Table 1. Collision Data- Moving and Stationary Marbles

Number of Flicked Marbles	Number of Stationary Marbles	Number of Marbles that Leave the Runway
1	4	1
2	3	2
3	2	3
4	1	1

Table 2. Collision Data- Moving Marbles

Number of Marbles on Right Side of Runway	Number of Marbles on Left Side of Runway	Number of Marbles that Leave the Right Side of the Runway	Number of Marbles that Leave the Left Side of the Runway
1	1	1	1
1	2	2	0
1	3	3	0
1	4	4	0
2	2	2	0
2	3	3	2

Post-Lab Questions

1. What kind of collision is exhibited by the marbles in this experiment and why?
2. When one marble hit the end of the line of marbles, how many shot off the other end? Describe the momentum of the set of marbles before and after the collision (assume elastic collisions).
3. How did the speed of the marble that comes off the end of the line change as you increased the speed of the marble that travels down the chute? Use what you know about the conservation of momentum to describe what is happening.
4. What happened when you sent two marbles down the runway? Is this what you predicted? Explain why or why not.
5. How did the result change when both marbles were moving toward each other before the collision?
6. What do you predict would happen to two marbles after a collision if you slowly rolled a marble down the runway and then flicked a second marble faster in the same direction?

Procedure for reference:

In this experiment you will demonstrate transfers of momentum similar to those of the Newton's Cradle system (Figure 1). The velocity of a marble after impact depends on the original velocity and the mass of the objects at hand. PROCEDURE Part 1 1. Use two rulers and make a runway between them by laying them flat on a level surface with the edges of each ruler parallel. The runway should be just wide enough for the marbles to pass through. 2. Line up four marbles in the center of the runway and ensure they are all touching. 3. Take the other marble and place it at one end of the runway. Flick it so it collides with the other marbles. Observe what happens to the four stationary marbles. 4. Try different speeds for flicking the marble into the four stationary marbles and observe how that changes the collision. Record the number of marbles that leave the runway in Table 1. 5. Repeat Steps 3 and 4 with three stationary marbles in the runway and two flicked marbles. 6. Repeat Steps 3 and 4 with two stationary marbles in the runway and three flicked marbles. 7. Repeat Steps 3 and 4 with one stationary marble in the runway and four flicked marbles. 8. Repeat Steps 3 and 4 with a new combination of stationary marbles in the runway and flicked marbles. Part 2 1. Use two rulers and make a runway between them by laying them flat on a level surface with the edges of each ruler parallel. The runway should be just wide enough for the marbles to pass through. 2. Identify one end of the runway as the left side of the runway and the other the right side of the runway. 3. Line up one marble at each of the runway. 4. Flick the marbles so they experience a head-on elastic collision. 5. After the collision, record the number of marbles that leave the right and left side of the runway in Table 2. 6. Try different speeds for the marbles and observe how that changes the collision. 7. Repeat Steps 3 - 6 for the combinations of marbles in Table 2.