Laboratory for 8/26/03

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. In such a case, include any other graphs that you use.)

 

2. Acceleration of Humans

This exercise will be done with groups of 8 or more individuals. Choose one member of the group as the sprinter, one member in charge of operations, and at least 6 individuals as timers. Your goal will be to determine the average velocity and average acceleration of the sprinter as a function of time.

Place cones along a level surface at equal spatial intervals. Place the timers with stopwatches at each cone location. Be sure that the procedure 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 and that the six measurements are over a "reasonable" distance.)

Before beginning calculations, there will be a group discussion on how to calculate the average velocity and acceleration from the measurements that you have made. Note that, unlike in the previous section, you have measurements at equal intervals of space, not time!

In your report, fully describe the technique you used. Plot average velocity vs time and average acceleration vs time. Discuss qualitatively the results. (Error estimation is not required for this section.)