Laboratory for 1/26/99

Acceleration

1. 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 to determine the value of g, the acceleration due to gravity in the lab. Discuss a plan of action with your partner before beginning measurements. The goal is to determine the acceleration due to gravity with as much accuracy as possible and to determine, within error, if g is truly a constant. You may use any appropriate calculations, averaging techniques, or graphs you wish, but your method should make use of all 10 points. The following should appear in your lab report.

  1. Fully describe your method, clearly stating how your calculations will correctly yield a value for g.
  2. Estimate the error in your value of g based upon the accuracy of your measurements and/or consistency of individual calculations.
  3. Include at least a plot of position vs time. You may wish to calculate g using graphical techniques. Of course, include any other graphs that you use.

 

2. Acceleration of Humans

This exercise will be done with groups of 7 or more individuals. Choose one member of the group as the sprinter. Your goal will be to determine the average velocity and average acceleration of the sprinter as a function of time.

Discuss a plan of action with your partners. Stopwatches, measuring tapes, and markers are avaliable. You may request additional equipment from the instructor. Decide how you will calculate the average velocity and acceleration from the measurements that you will make. Design a plan that will minimize the effect of the reaction times of both the sprinter and the timers. In consideration for the sprinter, try to minimize the number of trials he/she has to perform. Make a least six measurements over a "reasonable" distance. When you have finalized your plan, discuss it with the instructor.

In your report, fully describe the technique you used. Plot average velocity vs time and average acceleration vs time. Discuss the results.