1. Collision Situations

1. Screw a rubber bumper (Figure 1) into each force sensor.
2. Set each force sensor on the 50-N setting.
3. Zero the force sensors before each trial by pushing the "Zero" button next to the green arrow that starts data collection.
4. Check to see that the positive direction (i.e., to the right) is defined appropriately for each force sensor.
   1. Push in on the force sensor mounted on the right of the cart; this should result in a positive force reading. Push in on the force sensor mounted on the left of the cart; this should result in a negative force reading.
   2. If both are wrong, simply reverse the position of the cart.
5. If only one is wrong, go to the "Experiment menu" and select "Setup Sensors." Choose the appropriate force sensor and select "Reverse Direction."
6. The first collision involves carts of equal mass. Designate one cart to be stationary prior to the collision. The other cart will be given an initial velocity toward the stationary cart so that the carts collide.
7. Hit the "Collect" button (the green arrow) before pushing one cart toward the other. Give one cart a small shove, release the cart, and observe the collision. Peak force values between about 8 and 20 N should be observed in a typical trial. Adjust the push if the peak force values are much smaller than or much larger than this range.
8. After the collision, the computer will display a graph of "force vs. time," as recorded by each force sensor.
   1. If the graphs do not appear, reverse the triggering.
   2. After hitting the "Collect" button, no data is actually recorded until one of the force sensors records a value above (or below) a certain trigger level. However, if the trigger level is set to a positive value and the force sensor is only giving negative force values, or vice versa, the computer will never receive the signal telling it to record data.
   3. To check, or reverse, the trigger setting, press the "Data Collection" icon (immediately to the left of the "Zero" button) and select the "Triggering" tab.
9. The two options used in this experiment are "Increasing across 0.2 N" and "Decreasing across -0.2 N." If one of these settings is not causing the necessary triggering, switch to the other.
   1. In the second collision, the stationary cart should have 2-3 times the mass of the cart that is moving prior to the collision. To achieve this, add one or more weights to the stationary cart. Repeat the process (see the steps below).
   2. Designate the higher-mass cart to be stationary prior to the collision.
   3. Hit the "Collect" button and push the lower-mass cart toward the higher-mass cart.
   4. The computer will display the two "force vs. time" graphs.

In the third collision, the cart that moves prior to the collision should have 2-3 times the mass of the stationary cart. Achieve this by transferring the extra weight(s) from one cart to the other. Repeat the process of carrying out the collision and collecting the data.

2. Pushing and Pulling Situations

1. Replace the rubber bumpers on each force sensor with hooks.
2. Hook the carts together to allow one cart to push or pull the other cart.
3. Reverse the triggering condition, as described in step 1.8.
4. Start with carts of equal mass.
5. Hit the "Collect" button.
6. Either pull or push one of the carts so that it pulls or pushes the other cart, respectively, or rock it back and forth so that there both pulling and pushing occur.
7. Give the cart being pulled and/or pushed 2-3 times the mass of the other cart. Repeat the data collection process.
   1. Record the "force vs. time" data for this pushing/pulling scenario.
8. Give the cart doing the pulling and/or pushing 2-3 times the mass of the other cart. Repeat the data collection process.
   1. Record the "force vs. time" data in this pushing/pulling scenario.