Pendulum Simulation

Experimental Procedure

In this experiment, we will use PhET Simulation to examine the relationship between the three characteristics of a pendulum, namely: the initial angle of the string, mass, and length. To examine these characteristics one at a time, we will perform three separate data collections (Part A, B, and C of this lab).

• Open the Lab section (the third window) in the simulation below.

• Explore the available functions to change the initial angle, mass, and length of the pendulum.

Part A. Investigating T(Ѳ)

In this part of the experiment, you will be changing the starting angle of the swing. Both mass and length must not be changed in this part of the experiment. What do you think will happen with the pendulum period when the initial angle increases? Will it decrease, increase, or remain the same as you change the angle of oscillation? Write down your prediction/hypothesis.

• Set a desired length and mass (Figure 3).

• Set pendulum at 5° (Figure 2).

• When the pendulum swings, use period timer to measure the period (check the period timer box in the left lower corner of the animation (Figure 4).

• Repeat the steps above for a few angles, e.g. 10°, 15°, and 20°.

• Collect your data in a table.

Derive a conclusion based on the collected data. Does the conclusion confirm your prediction?

Part B. Investigating T(m)

In this part of the experiment, you will be changing the mass of the bob. Both the angle of oscillation and length must not be changed in this part of the experiment (5° and the original length) How will adding mass affect the pendulum period? Write down your prediction.

• Begin with a small weight, e.g. 0.1 kg (Figure 3). Make sure that you do not change the pendulum's length.

• Set pendulum at 5° (Figure 2).

• When the pendulum swings, use period timer to measure the period (check the period timer box in the left lower corner of the animation (Figure 4).

• Repeat the steps above for a few masses, e.g. 0.5 kg, 1 kg, and 1.5 kg (Figure 3).

• Collect your data in a table.

Derive a conclusion based on the collected data. Does the conclusion confirm your prediction?

Part C. Investigating T(L)

In this part of the experiment, you will be changing the length of the pendulum. Both the angle of oscillation and mass must not be changed in this part of the experiment (5° and fixed mass) . What will happen with the pendulum period when its length increases? Will it decrease, increase, or remain the same as you change the length? Write down your prediction.

• Begin with a short pendulum, e.g. 0.4 m (Figure 3). Make sure that you do not change the pendulum's mass.

• Set pendulum at 5° (Figure 2).

• When the pendulum swings, use period timer to measure the period (check the period timer box in the left lower corner of the animation (Figure 4).

• Repeat the steps above for a few lengths: 0.6 m, 0.8 m, and 1.0 m (Figure 3).

• Collect your data in a table.

Derive a conclusion based on the collected data. Does the conclusion confirm your prediction?

Part D. Comparing the experimental and calculated values

Calculate T using the provided formula

Find percent differences between the experimental and calculated value. What are the sources of error?

Explorations

1. Simple pendulum can be used to find the gravitational acceleration. Knowing the period of pendulum, find the gravitational acceleration g and compare to the accepted value of 9.81792 m/s² (source).

2. Since the value of g depends on the distance form the center of the Earth or altitude (Figure 7), is it possible to find the height of a hill or a skyscraper performing the described above experiment?