NSC 101 Laboratory for 1/27/98

Measuring "g"
The Behr freefall apparatus will produce a strip of waxed paper with small dots showing the position of a freefalling "torpedo" at equal intervals of 1/60 of a second. (Note that because of the manual release, the time between the first and second dots is not known.)
Make a systematic selection of at least 10 dots between the top and bottom of the strip that you will use to determine the value of g in the lab. Discuss a plan of action with your partner before beginning measurements.
You should :

• Make a table of positions and time. You may take the first position to be at t = 0.
• Make a plot of position vs time. How does it look? Is it a straight line?
• Calculate the average velocity between each of the dots and make a plot of average velocity vs time. How does it look? Is it a straight line?
• Calculate "g" values using the average velocities. Find the average of all your values.

The goal is to determine the acceleration due to gravity (g) with as much accuracy as possible and to determine if g is in fact a constant.

It is important that you think about the following:

• The distance between the dots divided by the time is the average velocity between those dots. Is the instantaneous velocity equal to the average at any point?
• How does the spacing between the dots effect the accuracy of your velocity calculations?
• Acceleration is the change in velocity divided by the time. But you must consider carefully how much time takes place between one velocity and the next.