PERIODIC MOTION:
PENDULUM
PROCEDURE
The set up for this experiment is simple. The pendulum is suspended by a cord and the period is measured by allowing it to oscillate past a photogate timer. The timer is interfaced so that it measures the elapsed time for one full swing, or the Period.
2. Set up the pendulum with a 1.5 meter length. Enter this value in cell B11 on the Worksheet. The string should be tied with a slip knot ( the same kind you tie your shoes with). Place a 50 g mass on the mass holder, giving the bob a total mass of 100 g.
3. With the pendulum perfectly still at equilibrium, carefully adjust the photogate so that it is placed jaws up at the equilibrium point, but so that it will not interfere with the swing as the pendulum passes.
4. Carefully draw the pendulum back and release it cleanly to check that it will swing without hitting the photogate. You should not pull it back more than about 10 cm from equilibrium. Practice until you learn the technique.
5. Make sure that the photogate cable is attached to the DataLogger box, and that the unit is switched on.
6. Open the Pendulum Timer link. A Period vs. Time graph will appear.
7. Displace and release the pendulum to start it oscillating without hitting the photogate. Click the Collect button on the computer.
8. Allow the pendulum to swing for about 200 seconds, then hit Stop on the timer window. Select the ANALYZE...Statistics menu item. From the floating box on the Period vs. Time plot, record the the Mean Period in cell B12 on the Worksheet.
9. Select the Table Window and record the very first period value and the very last period value in cells B13:B14 on the Worksheet.
10. Repeat the same procedure for three more pendulum lengths: 1.25m, 1.00 m and 0.75 m. Record the data in cells C11:E14 on the Worksheet.