29 Appendix: Detector and Ball Setup
Detector Setup
Your equipment for the experiment should already be set up upon your arrival as shown in Figure 1. If it is not, please follow the setup instructions below:
1. Plug in either of the two plugs from the timer switch into the Photogate port on the Control Box. The second plug does not attach to anything.
2. The telephone extension cord connects from the Control Box (Signal to Drop Box port) to the Drop Box. Plug the Motion Sensor into the interface. Note that the Motion Sensor is not centered in the Motion Sensor Guard. This decreases the chance of a signal returning off the guard cage.
3. Plug in the AC adapter and connect it to the Control Box.
4. Set the Motion Sensor to the cart position and turn the sensor to the 900 position so it points vertically upward.
Ball Setup
The balls should also already be set up for this experiment before your arrival. The key things to look for are a metallic end on one side of the ball (either a taped washer, or connected staple) as shown in Figure 2 (a), and a piece of cardboard attached to the other as shown in Figure 2 (c). If any of the balls you have chosen are missing these two key elements, please follow the setup instructions below:
1. Peel backing from any extra labels that are attached to the ball and attach washers to the desired ball with Scotch tape as in Figure 2 (a). Note: the styrofoam balls may have a metallic parts that was inserted into it.
2. Cut a 4 by 4 cm square from an index card and tape it to the side of the ball 180 degrees from the washer as shown in Figure 2 (b). The square should be directly opposite from the washer so it will be on the bottom of the ball and as flat as possible. This will dramatically improve the signal return from the falling ball.
3. For some of the other balls, the cardboard layout may need to be different in order to better account for the different geometry. Cut a 4 by 4 cm square with 2 cm tabs and form it into a half box as shown in Figure 2 (c). In this case, we are using a golf ball.
