PhysicsLAB

1995 Videoconference Lab
Sand Spring


Purpose: The purpose of this lab is to produce an oscillation that has a varying amplitude and period. As the sand leaks from the funnel, the period of the spring's oscillation changes .

springperiod.gif (1246 bytes)

since the mass is constantly decreasing. Moreover, the spring's amplitude also changes as more and more sand leaves the funnel.

sandfunction.gif (2060 bytes)

A typical graph of this type of oscillation would look like the following sample.

sandspring.gif (4396 bytes)

Procedure (set-up):

One member of the group should go to the computer, open PSL and SELECT the experiment entitled First Steps. Now go to RESET PARAMETERS and change the Duration to 15 seconds. Remain in RESET PARAMETERS and change the Number Format to 6,5,6,5 so that as many decimals as possible are recorded from the PSL program for your graphs. Next go to RUN EXPERIMENT and Calibrate your distance probe. Check the Room Temperature with the thermometer on the back wall and maximize your Data Rate. Then escape back to Preview and check that your machine has the correct COM port. If the PSL doesn't start, go to COM and change the port from 1 to 2 or vice-versa. Then return to Preview and verify that the probe is taking data.

A second member should verify that the probe is looking at the blue cardboard attached to the top of the funnel - only slight adjustments should be necessary! He/she should then fill the funnel with sand, keeping a finger over the exit hole so that the sand does not immediately run back out, and use the counterweights (slotted masses) to level the cardboard. The purpose of the box is to catch the sand as it leaves the funnel, so please make sure that it is in place before beginning the experiment. While the probe is in Preview and the exit hole of the funnel is covered, verify that the probe is seeing the cardboard by moving the filled funnel carefully up and down -- DO NOT USE LARGE AMPLITUDES! 5-6 cm is MORE THAN ENOUGH! When everything is working, escape from Preview and go to Start.

Procedure (data collection):

Since the sand leaves quickly, the person releasing the spring should tell the PSL operator when to start the probe. Try to release your spring with a small steady amplitude and a minimal amount of rotation (twisting). Watch your graphs. The oscillations should minimally have either a constant set of smooth crests OR smooth troughs -- it is not absolutely necessary to have perfect oscillations in both places. When you have a good trial, so to DATA, cursor down to Spreadsheet, press enter and then press F6 to change drives to A. Next press the grey insert key to save your first satisfactory trial. Use the following format for your filename: your period number, then aide letters, then SD1. For example a file in 4th period might look like: 4mnopSD1. REMEMBER that you do NOT put an extension on files in PSL, the program will add its own. Then type your group's last names as a description. Finally, carefully refill the funnel and obtain a second trial. Save this one as SD2. Run your trials as accurately AND quickly as possible, remember that at least one other group needs to use your lab station before the period is over.

Record here both filenames and on which data disk your information is saved. Remember, do NOT remove a disk from the A drive until the green light is off - otherwise your files will not be saved correctly. You will analyze both of these data files tomorrow in class.

_________SD1             ___________SD2             data disk #_____

When you are finished with both trials, leave the spring & funnel suspended and the sand in the box. Please sweep up and return any sand which got scattered onto the table back to the box. F9 the PSL screen so that the next group can begin. Put these directions into the basket for safe keeping until tomorrow's class. DO NOT take them from the room. I need to use them this afternoon to correlate the data files.

If you have not done the water spring, proceed to one of those stations and politely wait your turn. You need to complete BOTH set-ups today so that you can analyze both sets of data tomorrow.




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Catharine H. Colwell
All rights reserved.

PhysicsLAB

Mainland High School
Daytona Beach, FL 32114