Pendulum Essay, Research Paper

Arif Zaman

9/12/00

Hon. Matter/Energy Pd.8

A Swinging Time

Purpose: To determine the factor(s) that affect the period of a pendulum.

Hypothesis: The factors that I think will affect the period of the pendulum are the displacement and the suspended mass because if the mass of the bob is a lot than it will take more force for the pendulum to swing and if there s a high displacement it will give the pendulum more energy to complete the cycle.

Materials:

stopwatch

100, 200, and a 500g bob

protractor

meter stick

string

Procedures:

1. Gather materials.

2. Start the string at a length of 130cm.(control)

3. Attach a 200g bob(control) to the bottom of the string.

4. Make the displacement 30cm by pulling the bob 30cm away from the center. Do this with a meter stick.

5. Let go of the bob and allow one full cycle before starting the stop watch.

6. Stop the stop watch after the bob returns.

7. Record data.

8. Repeat steps 1-7 with a displacement of 60cm. Then try a displacement of 90cm.

9. Now repeat steps 1-7 with a length of suspension of 130cm,170cm, and 210cm. The controls are a bob of 200g and a displacement of 90cm.

10. Finally repeat steps 1-7 with 100g, 200g, and a 500g bob. The controls are a displacement of 90cm and a suspension of 130cm.

Observations: controls-length of suspension 130cm, bob 200g

How Displacement Affects the Period of a Pendulum

Displacement Period

30cm 2.72 seconds

60cm 2.37 seconds

90cm 2.34 seconds

controls- displacement 90cm, bob 200g

How Length of Suspension Affects the Period of a Pendulum

Length of Suspension Period

130cm 2.34 seconds

170cm 2.55 seconds

210cm 2.87 seconds

controls- displacement 90cm, length of suspension 130cm

How the Bob Affects the Period of a Pendulum

Bobs Period

100g 2.29 seconds

200g 2.34 seconds

500g 2.69 seconds

Conclusion:

The purpose of this experiment was to determine the factor(s) that affect the period of a pendulum. The independent variables were the length of suspension, displacement, and mass (bob). The dependent variable was the period of the pendulum.

My hypothesis was that the suspended mass and the displacement would affect the period of the pendulum. My hypothesis was partially correct. I learned that the length of suspension also affects the period of a pendulum. The lower the length of suspension is the lower the time for a pendulum to complete a cycle.

Connections/Textbook Research:

1. independent variable- The variable that s regulated by the scientist. The independent variable can be chosen before conducting the experiment. e.g. time.

dependent variable- The variable that changes as a result of the independent variable. This is the unknown factor and the reason for doing the investigation. The values of the dependent variable are determined only after the experiment has been conducted.

e.g. speed. Source- Reference 5 H. M and E Graphing techniques.

2. In this experiment the independent variables were the length of suspension, displacement, and the mass (bob) because they were the variables we could change. The dependent variable was the period of the pendulum because that was what we were measuring.

3.It s important to test one independent variable at a time because if you test more than one at a time there will be no control and you won t know which variable affected the experiment.

4. The term control means An experiment ran without a variable(s) in order to show that any data from the experimental setup was due only to the variable that was being tested.

This is a controlled experiment because we always kept two variables the same.

Source- Exploring Physical Science, 1997, page 13.

5. qualitative observation- the observations of the characteristics of something.

quantitative observation- the observation of the magnitude, size, extent, or amount of something. Source- http://www.harcourt.com/dictionary/

6. A hypothesis is a proposed solution to a scientific problem. A theory is a logical, time-tested explanation for events that occur in the natural world. The two are similar, however, a hypothesis is your or the answer to the problem. A law is a summarized statement of observed experimental facts that has been tested many times and is generally accepted true. A law was once a theory but was proven correct after many trials. I think that this was a quantitative lab because we were observing measurements of time, length, and mass. Source- Exploring Physical Science, 1997, pages 8-9 and 12-14.

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