## Procedure

1. Push the CALIBRATE button in order for the applet to work with the clock speed of your machine. You only need to do this once.

2. Select "Moon" from the planet selector box underneath the stopwatch.

3. Pushing the DROP button will cause to ball to fall.
4. See how long it takes for the ball to drop 6 meters. Do this a few times to make sure that your machine registers the same time (to within 0.01 second) each time. The correct time is 2.71 seconds.

5. There is a red and green marker available on the ruler. Their default positions are at 0 and 6 meters. Move your mouse to the 1m mark on the ruler and click it. That will position the green marker there (note: you can grab the marker with the mouse and move it as well). Now go to the bottom and grab the red marker and move it to 3m.

6. Push the DROP button again and the stopwatch will only time between 1 and 3 meters. Record this time.

7. Now move the green marker to 0m and the red marker to 2m and repeat and record the time. Do the same for intervals of 2 to 4m, 3 - 5 m and 4--6m.

 The average velocity is determined by the time it takes for the ball to go a given distance. Compute the average velocity for each of the two meter distance units that you have previously defined. As in the previous exercises involving the real ball dropping make plots of average velocity vs height above the surface and total distance travelled versus time. Now we will simulate what we did in the Atrium but this time acquire a lot more data with better precision. This part only will work on the Moon so make sure moon is selected. Using the procedure outlined above with the red and green makers set them a part at units of 1/4 of a meter. Starting from 0. So your first measurement of time is from 0.0 to 0.25, your second one is from 0.25 to 0.50, etc continuing until the last measurement is from 5.75 to 6.00. Make a plot of total distance travelled versus time. From that plot determine how long it will take for the ball to reach a distance of 24 meters. Here finally is a test to see if you now empirically know the relation between distance travelled and time for objects in Free Fall: Experimentally determine the distance which an object on the Moon will fall in one second. Now predict at what distance the object will be in two seconds. Test your prediction. The total freefall time is 2.72 seconds. At what distance will the object have travelled in 1/2 this time? Again, check your answer. From these experiments you should now be able to write down an equation that relates distance travelled to elapsed time. What is this equation? (no fair looking it up in a book).