Conservation of Momentum

1. Understanding the photogate timer.

1. Using a balance, measure and record the mass of each glider.
2. Place one glider on the track with one photogate timer.
3. Set the photogate timer to the "gate" setting.
4. When the glider passes through the photogate, it will record the time at which the flag above the glider passes through the gate. On a return trip, the photogate will not display a new time. Switch the toggle to "read" so that it will display the initial time plus the time of the second pass through the gate.
5. The flag is 10 cm long; determine the velocity of the glider using the fact that the speed is distance divided by time.
6. Send the glider through the photogate several times, including the return trips after it has bounced off the far wall, and measure the velocities in order to become familiar with the equipment. Remember that velocity has a direction. Let the initial velocity direction represent positive and the opposite direction represent negative velocity values.

2. Two gliders of equal mass.

1. Place two gliders and two photogate timers on the track, as in Figure 1.
2. Use Equation 3 to determine the expression for the final velocities. In this part of the experiment, glider B will start from rest.
3. Give glider A some initial velocity so that it will collide with glider B. Record the initial velocity of glider A, as well as the final velocities of each glider. Do this three times, record your results, and compare them to the theoretical prediction.

3. Two gliders of unequal mass.

1. Add 4 weights to glider B, which will double its mass. Repeat steps 2.1-2.3.

4. Equal masses not starting from rest

1. Remove the weights from glider B.
2. Repeat steps 2.1-2.3, but give glider B an initial velocity as well, in the direction of glider A.