# Momentum & Collisions

## Totally Inelastic Collisions

### Purpose:

To qualitatively investigate conservation of momentum by examining totally inelastic collisions.

### Background Theory:

When two carts collide, we know that the total momentum of the system should be conserved, as long as there are no external forces acting on the system. That is, Pi = Pf, where Pi and Pf are the total momenta before and after the collision, respectively.

### Procedure:

#### A. Carts with Equal Mass

Orient the carts so their velcro bumpers face each other. In the collisions, they MUST stick together.

1. Place one cart at rest in the middle of the track. Give the other cart an initial velocity toward the cart at rest.

 Prediction Observation
2. Start with both carts at opposite ends of the track and push them toward each other with about the same speed.

 Prediction Observation
3. Start with both carts at one end. Give the first cart a slow initial speed, and the second a faster speed so it catches the first about halfway down the track.

 Prediction Observation

#### B. Carts with Unequal Mass

1. Place two mass bars on one of the carts. Now its mass is about 3 times the mass of the other cart. Put the 3M cart at rest in the middle of the track and push the other toward it.

 Prediction Observation
2. Put the 1M cart in the middle and push the other toward it.

 Prediction Observation
3. Start the carts at each end of the track. Give them about the same speed toward each other.

 Prediction Observation
4. Start both carts at the same end of the track. Give the 1M a slow speed, and the 3M a faster speed so that it collides with the first.

 Prediction Observation
5. Start both carts at the same end of the track. Now give the 3M a slow speed, and the 1M a faster speed so that it collides with the first.

 Prediction Observation

## Elastic Collisions

### Purpose:

To qualitatively investigate conservation of momentum by examining elastic collisions.

### Background Theory:

When two carts collide, we know that the total momentum of the system should be conserved, as long as there are no external forces acting on the system. That is, Pi = Pf, where Pi and Pf are the total momenta before and after the collision, respectively.

### Procedure:

#### A. Carts with Equal Mass

Orient the carts so their magnetic bumpers face each other. The carts MUST bounce without hitting.

1. Place one cart at rest in the middle of the track. Give the other cart an initial velocity toward the cart at rest.

 Prediction Observation
2. Start with both carts at opposite ends of the track and push them toward each other with about the same speed.

 Prediction Observation
3. Start with both carts at the same end. Give the first cart a slow initial speed, and the second a faster speed so it catches the first about halfway down the track.

 Prediction Observation

#### B. Carts with Unequal Mass

1. Place two mass bars on one of the carts. Now its mass is about 3 times the mass of the other cart. Put the 3M cart at rest in the middle of the track and push the other toward it.

 Prediction Observation
2. Put the 1M cart in the middle and push the other toward it.

 Prediction Observation
3. Start the carts at opposite ends of the track. Give them about the same speed toward each other.

 Prediction Observation
4. Start both carts at the same end of the track. Give the 1M a slow speed, and the 3M a faster speed so that it collides with the first.

 Prediction Observation
5. Start both carts at the same end of the track. Now give the 3M a slow speed, and the 1M a faster speed so that it collides with the first.

 Prediction Observation