Question

Design an experiment to test physical quantities that affect the period of a pendulum. Use Experiment 1: Oscillating Spring to guide your experimental procedure. You are provided the mass set and string for your experimental materials. The period should be tested against a change in amplitude (use angles less than 30 degrees), a change in mass, and a change in length, one variable at at time using a wide range of data. Use your results to verify which variable(s) effect the period of the pendulum as given in the introduction. In Experiment 1: Oscillating Spring, the spring constant was able to be determined. In a similar fashion, determine the value of g and include an error analysis in your report. Include the calculation of this constant in your data analysis. I just need help figuring out the experiment for the pendulum.

Answer 1

Experiment for the pendulum:

1. Present a Demostration of a simple pendulum to the students i.e take a string ranging from 40 to 60 cm and a weight of 10 to 100 gm. Show/Explain the pendulum movement as you release the mass from one point at a certain angle. Now pose questions to the students such as '' How can you change the time required by it to complte single osicillation?'' or ''which variable you should change to affect the time period?''  

2. Make groups in the class and let them obserbe the effect of changing variables one by one.

i.e Instruct them to change the length of the pendulum and measure the time period for different lengths after that do the same for the mass and the angle as well.

3. Precautions must be taken while measuring the length of the pendulum as you must remember the length is measured from center of mass of the object which can vary a little whith object to object.

Now the results:

A) Mass :: Does it affect the Time Period?

Well the answer you know very well, it should not affect the period but student will certainly come to the conclusion that it does because of the real time errors such as measuring errors, effect of wind etc.

Well to solve it you just need to ask for the %change in the time period with respect to the %change in the mass, it will be very small could be neglected.

B) Angle (less than 30) :: Similar to the for the angle less than 30 degree the time period should be constant but the real time results can vary a little and you can adopt similar idea of %change that we adopted for effect of mass.

C) Length :: Well everyone will certainly agree that change in the length is affecting the time period, the question is how much and what is the relation between them.

In this case you need to extend the range (different lengths of pendulum) to plot a time vs length graph to find out the relation between them.

or

you can plot a graph between time vs square root of length or Squre of time vs length and compare your results with it.

That's it.