Buggy Lab Extension

We often repeat labs to use other means of collecting data or extend the learning from the previous lab. Here, we are reinforcing the concept that displacement = velocity * time + initial displacement or d = v_ot + d_o.

This lab uses the program GENDOST available as generic.83p on a Texas Instruments calculator attached to a CBR or a motion detector with a CBL. The program firsts asks the student to determine a baseline or origin for the graph. We ask the students to place the cart about 1 meter from the motion detector. When the student presses ENTER, the motion detector measures and records the starting distance. Depending on the speed of the cart (we sometimes use balls and roll them), select the number of data points to be collected and the time interval. Faster objects should have fewer points and/or shorter collection periods. In general, we collect 50-99 points at 0.02 to 0.05 second intervals. The student then places the buggy in front of the motion detector and starts it moving away from the detector. When the buggy is 0.5 meters from the motion detector (inaccurate data will be collected within this range), the student presses ENTER to begin collecting data. Note: GENDIST assumes the motion detector is in a fixed position and that distance between the motion detector and the origin established at the start of the program is positive.

The graph may appear similar to the one below.

From this graph, students are expected to determine the speed of two (2) objects and answer such questions as:

1. If the slower cart starts 1 meter ahead of the other cart, how long will it take the faster cart to catch the slower cart? Where will the faster cart catch the slower cart?
2. If the carts are 5 meters apart with one headed towards the other, when and where will the "crash" occur?

If you are an educator or interested in this activity and wish to have more information, send an e-mail to jrynear@lps.org or jwelker@lps.org.