Practice with the simulation:
To begin with, select Earth, click the zoom out button. You will now see a 100 meter stick. Click the drop button. The readouts show:

• total travel time (i.e. the time it took to go 100 meters)
• Ball travel time (which in this case is the same as total travel time)
• total distance dropped
• velocity of the ball when it hits the ground.

For earth, the total travel time should be 4.52 seconds for 100 meters. Hit the reset button to move the ball back up to the top of its drop. Now move your mouse to the bottom of the yellow meter stick and click and hold the left mouse button. Drag the red horizontal line up until its at 70m (doesn't have to be exact). Now move your mouse to the top portion of the yellow meter stick and grab the yellow line and move it to 20m.

Hit drop again and notice that B time now reads 1.77 seconds (or something close to that). This time corresponds to the amount of time it took for the ball to do from the top marker (blue one at 20 meters, to the bottom one, red one at 70 meters).

We will make use of these markers in the procedure below:

1. Go to the moon and drop the ball 100 meters on the moon and compare the times to the 100 meter free fall done on Earth. What is the ratio of free fall times on the moon compared to the earth?
2. Hit reset and go back to the earth. Hit zoom in to drop the ball 10 meters. What is the ratio of freefall times between 100 and 10 meters?
3. Do the same experiment on Mars for heights of 10 and 100 meters - is the ratio of freefall times the same?
4. Let's stay on Mars and use 100 meters. Move the bottom marker to 50 meters and determine the ball travel time from 0 to 50 meters.
5. Now move the bottom marker to 100 meters and the top marker to 50 meters. Before dropping the ball, state if you think the time will be same or different and why you think that. Now drop the ball record the time and take the ratio of the 50-100 m transit time to the 0-50 meter transit time.

1. Okay let's go back to earth. Set the bottom marker to 10 meters and record the 10 meter drop time. Now set it to 20 meters and do the same. Now set it to 30 meters and do the same. Now set it to 40 meters and do the same thing. You should make a graph (but you don't have to submit it) of free fall time vs distance. Is this graph a straight line? Use the graph to predict how long it would take for the ball to drop 60 meters. Make a measurement and state (honestly) how close or far off your prediction was.
2. You have enough data to now determine the following, but you can run the expirement to test your answer.

   a) If it takes 2 seconds to fall 20 meters on the earth, how long would it take to fall 80 meters?

   b) The surface gravity on Jupiter is 2.4 times higher than that of the earth. It takes 4.5 seconds to fall 100 meters on the earth and the impact velocity of the ball would be 44 meters/second. How long would it take to fall 100 meters on Jupiter and what would that impact velocity be.

   Explain your reasoning in both cases.

When done, submit your worksheet by clicking on the words "publish to global view" (the first item under reporting tasks).