GRAPHS AND TRACKS

Today’s lab will give you another opportunity to explore the relationships between an object’s motion and the graphs that describe the motion: x-vs-t, v-vs-t, and a-vs-t. Don’t try to do the minimum required and get finished quickly -- spend some time thinking carefully about what you are doing. I have not encountered another program that is so useful at building intuition. If by the end of the lab, you do not feel that you have mastered motion graphs, I would recommend spending some more time working with the program. It is available on the network under the DEPARTMENTAL APPLICATIONS, PHYSICS APPLICATIONS menu available from the 'DOS … by Automenu' choice on the program list of the start button on the Hamilton computer lab computers. This program is not accessible from other locations.

The program Graphs and Tracks has two parts. In Part 1, you are given the motion graphs for a ball rolling on a track. You must then design a track that will produce the proper motion. You do this by changing the elevation of the various straight segments of track and altering the initial position and velocity. In Part 2, you are show an arrangement of the track, and you must construct qualitative motion time graphs by using a specialized drawing program.

Part 1

• Start the program by double-clicking on the 'G & T 1' icon. This icon should be in an open window on your desktop. If it is not, ask for assistance in finding the proper icon.

• Choose instructions on the first program screen. Go through the instructions.

• Next choose ‘Free Exploration’ under the ‘Options’. Spend about 5 minutes creating different tracks and observing the motion graphs produced.

• Now proceed to the ‘Examples’. Begin with Example 1. When you finish each example, write a brief description of the motion, draw the track setup, and list the initial positions and velocity as well as the number of rolls required for success (there is no penalty for a high number of rolls). After you have done this, look at all three graphs one more time. Think about how the graphs are related to each other and to the slope of the various sections of track. If you have trouble with Example 1, do Example 2 before proceeding to the more difficult tracks.

• You have a choice of the other examples to complete: Do ONE of #3 or #4, one of #5 or #6, and one of #7 or #8. Don’t forget that it can be helpful to move between the three graphs. If you get stuck, click on ‘Help’ for a hint. If you feel like the solutions are too easy, try using only the position graph and not looking at the others.

Part 2

• Next, exit the program and start Part 2. Again, go through the instructions. If you have never before used a drawing program, the instructions may not be sufficient to make you feel confident. If this is the case, ask for assistance before beginning the second examples.

• Complete the first two examples. To find out if you have the graphs correct, click on the question mark. Once the program verifies your work, draw the track and all three graphs in your notebook.

• Remember to describe what you have learned about the way that the three graphs (of position, velocity and acceleration versus time) are related to each other.