Pendulum Activity

In this activity, you and NO MORE THAN TWO OTHERS will explore the behavior of a simple pendulum, in order to understand a number of dynamics concepts.

The period of a pendulum, T,  is the time (s)  it takes for the pendulum to complete one oscillation. 

Primary Questions:

  1. How does the mass of a pendulum affect the period, T?

  2. How does the length of a pendulum affect the period, T?

  3. How does the displacement (amplitude) of a pendulum affect the period, T?

First:  Predict answers to the primary questions above.

Next:  Design and perform experiments to answer the primary questions above.  Be sure that any experiment isolates the correct variable, and that a number of replicates are performed (minimums: 5 different masses; 10 different lengths; 10 different displacements)

Finally:  Analyze the data you collected to determine the apparent relationship between the period T and the three variables, as well as the validity of your initial predictions.

From:  http://gorams.wssu.edu/physcilabs/Finished%20Pages/..%5CPhyscial%20Lab%20Web%5Cg-5a.htm:

A convenient and reasonably accurate way to measure the period of a pendulum is:

  1. Displace the bob to the right or left (the horizontal displacement) by a distance equal to or less than 10% of the length of the pendulum and release it. 

  2. Start your timer as the bob passes through the equilibrium point. (NOTE: The start of the timer represents 0 cycle and not one cycle.

  3. Allow the bob to swing through 25 complete oscillations and stop the timer at the end of the 25th cycle (oscillation).

  4.  Divide your time by 25. This gives the period of oscillation, T.

Materials:

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Ring Stand and Clamps

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String

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Masses

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Stop Watch

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Meter Stick

Write-up:

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Typed!

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Names

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Descriptive Title

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Introduction explaining the goal of the lab and your initial predictions

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Labeled diagram of experimental apparatus used

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3 data tables, with descriptive  titles

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2 Graphs:  Length v. T, and Length v. T2.  Set y int=0, include best fit line equation, and R2 value for 2nd graph.

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Conclusion which answers the following questions:

1)  How does changing the mass of the pendulum affect the pendulum's period?
 

2)  Which of the following laws best describes the effect on the period by varying the mass?

bullet    a) no effect
bullet    b) doubling the mass doubles the period
bullet    c) doubling the mass quadruples the period
bullet    d) quadrupling the mass doubles the period

3)  How does changing the length of the pendulum affect its period?
 

4)  Which of the following laws best describes the effect on the period by varying the length?

bullet    a) no effect
bullet    b) doubling the length doubles the period
bullet    c) doubling the length quadruples the period
bullet    d) quadrupling the length doubles the period

5)  How does changing the displacement of the pendulum affect its period?

5)  If you were to release your pendulum, regardless of amplitude, mass or length, it will eventually slow down in its swinging and come to a stop on its own. What effects cause this slowing down and stopping?

6) List possible sources of errors for...

bulleta) Mass portion of the experiment.
bulletb) Length portion of the experiment.
bulletc) Displacement of the experiment.

7) Based on your data, state an overall conclusion relating the period of a pendulum to its amplitude, mass and length (One formula where T~???).