Experiment Description:

In this Lab Experiment we are going to determine the acceleration of gravity (g) with the help of a simple pendulum. The period of the oscillations of a pendulum will be measured and used later to study the acceleration of gravity.

To investigate if the acceleration of gravity depends on the length or mass of the pendulum, you are going to use two different lengths for the pendulum and two different masses for the bob. One heavier (m1) than the other (m2). So, in total you need to investigate four different pendulums (four experiments):

Pendulum 1: Length 1 (longer string) and mass 1 (the heavier of your two masses)

Pendulum 2: Length 2 (shorter string) and mass 1.

Pendulum 3: Length 1 (longer string, same length as pendulum 1) and mass 2 (the lighter of your two masses)

Pendulum 4: Length 2 (shorter string, same length as pendulum 2) and mass 2.

Procedure:

1. Measure the length of the pendulum using the heaviest of the two masses (m1) for the bob.

2. Using a stopwatch measure the time needed for the pendulum to complete 10 oscillations. Start the pendulum's oscillations from asmall angle (approx. 5 to 8 degrees. You can use a protractor to measure the angle. Do not touch the string with protractor).

Important: A complete oscillation means that the pendulum comeback to the initial position from which it was released.

3. Change the length of the pendulum (make it shorter) and repeat step 2 using this new length.

4. Change the mass of the bob (now use the lightest mass m2) and using the same lengths as in the steps 2 and 3, repeat steps 2 and 3.

5. Calculate the acceleration of gravity g (Experimental value) for each of your four pendulums using the pendulum's equation: T = 2 (L/g)^1/2

Remember that in each of your four experiments, you are measuring the time for 10 complete oscillations and the length of the pendulum L.

Important: T, The Period of a pendulum is the time needed for a pendulum to complete one (1) oscillation around its equilibrium position.

T = (total time to complete 10 oscillations) / 10

6. Calculate the percent error in the calculation of gravity (Accepted or True value: 9.81 m/s²).

The Percent error is given by:

%error = (Experimental value - True value) x 100%

True value

7. Organize your data (you can use a table or chart) and WRITE AND SUBMIT A LAB REPORT. The Lab report must include definitions of the concept that you are studying in this Lab and an explanation of how you conducted the experiment. Also, all your data, main equations used for calculation of acceleration of gravity (g) and percent error for each one of your four pendulums. Send a picture of your pendulum.

Also, in your report you need to answer the following questions:

1. What are the possible sources of errors that affect the measurement of gravity (g) during this Lab experiment?

2. Does the value of gravity depend on the length of the pendulum?

3. Does the value of gravity depend on the mass of the pendulum?

How to produce a Lab Report?

Basically, a Lab report can have 3 parts:

1. Introduction.

2. Data Collection and Calculations.

3. Conclusions.

In The introduction (1) you need to define and explain a bit about the physical meaning the concept you are studying in The Lab. Besides, in this first part you need to explain a bit about the experiment; how do you conduct it.

In The data collection and calculation part (2) you need to present all the data (tables, etc) and information that you collected during the experiment. Also, you need to show ALL your calculations equations used, etc.

Finally, in your conclusions (3), you need to analyze the result of your experiment and to address al the questions in the hand out. In this final section you need to write about the sources of error and tell everything you learned during this Lab.

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