# 3 Ways to Create and Use a Pendulum

Pendulums are fun to play and easy to make! A pendulum is basically an object hanging from a fixed point that swings back and forth under the influence of gravity. Besides being able to be used on a wall clock to adjust the hands of the clock, or show the movement of the earth, the pendulum is also a great experiment!

## Step

### Method 1 of 3: Making a Pendulum

#### Step 1. Gather the ingredients

This pendulum experiment is easy to do at home. All the ingredients are easily available. For the purposes of this article, you will only be making one pendulum, but you can cut more at different lengths. So, make sure the length of the rope you have is more than 70 cm.

• Prepare two chairs and a long wooden ruler. You will use a chair and a ruler to make the outline of the pendulum. The pendulum will hang on the ruler between the chairs.
• Scissors are used to cut string and tape if you need to. Tape is used if you end up using a coin instead of a washer.
• The length of the rope should be at least 70 cm, but the longer the better. You can use string or wool, depending on what you have.
• A stopwatch is used to record the period of the pendulum and how the period changes when you change the angle or length of the pendulum.
• You can use five washers, or three coins as pendulum pendulums. These items make great weights to work with and are easy to find at home.

#### Step 2. Place two chairs back to back

Place the chairs about a meter apart, as you will be placing a wooden ruler across the backs of both chairs. Make sure the two chairs are facing each other because the front of the chair will block the curvature of the pendulum strings.

• Place the wooden ruler across the top of the chair and make sure the ruler is positioned straight between the backs of the two chairs. If the position of the ruler is skewed, this may make your calculations incorrect.
• Once the wooden rulers are stable over the backs of the two chairs, you can tape them down to keep them in place.

#### Step 3. Cut the rope to a size of 70 cm

This string will become one part of the pendulum. Next you need to add a pendulum or ballast. If you want to make more pendulums of varying lengths, you will find that the frequency of the pendulums (the number of times the pendulum swings back and forth per second) depends on the length of the string.

### Tie a string in the center of a wooden ruler. This is so that the pendulum does not hit the chair

#### Step 4. Tie five metal washers to the untied ends of the rope

This washer will become a pendulum, which will make it a pendulum. In addition to the washer, you can use three coins. Glue it carefully to the untied end of the rope.

### Method 2 of 3: Using a Pendulum

#### Step 1. Pull the string firmly at an angle from the wooden ruler

Do this by holding the end of the rope that is given a pendulum, which is a washer or coin. The frequency of the pendulum can change depending on the angle taken.

### For example, releasing a pendulum from a 90-degree angle on a wooden ruler will give it a different frequency of movement than, say, a 45-degree angle

#### Step 2. Let the pendulum swing

Make sure you release it so the pendulum doesn't hit anything while swinging. If the pendulum hits something, you have to start over. While letting the pendulum swing, you'll be timing the swing, so be prepared.

#### Step 3. Calculate the swing time

Start timing the pendulum as soon as you take it off. When the pendulum returns to its starting position, stop counting the time. It's helpful to have a friend do this, so you can set the pendulum while your friend is setting the stopwatch.

### One swing made by the pendulum is called the "pendulum period". You can also find out the frequency by looking at the number of times the pendulum swings back and forth per second

#### Step 4. Remove the pendulum again

Count the time to see if the pendulum spent the same amount of time as it did when it was first released. Make sure you remove it from the same angle. Any changes?

#### Step 5. Record your observations

Record the time of the pendulum's period and its frequency so that when you start doing creative things with the pendulum, you can see how things change.

• This will help you understand the two main applications of the pendulum. One to show the time, the other is called the Foucault Pendulum. To show the time, the movement of the pendulum adjusts the movement of the clockwise.
• The Foucault Pendulum shows the rotation of the earth. These pendulums are so large (sometimes more than two stories high) that they can swing for longer periods of time.

### Method 3 of 3: Doing Creative Things with a Pendulum

#### Step 1. Cut the second rope

Using a second, even third string can help you demonstrate the special properties of a pendulum. Cut this string shorter than the first, or give it a different weight.

• Cut a second string 35 cm long, if you want to test how different lengths of string affect the pendulum.
• Place the second rope 20 to 30 cm from the first, so that they do not collide while rotating.

#### Step 2. Change the weight of the pendulum

Test pendulums with different pendulum weights and see if there is a change in rotation and frequency. Take the time to see what the differences are, if any.

### Repeat a few times (about five times) and calculate the average time you recorded, or oscillations. This will produce the moving average of the pendulum

#### Step 3. Change the angle

While small angle changes tend to have no effect on the rotation of the pendulum, you can try making a very large difference and see how it works. For example, pulling one rope at an angle of 30 degrees and one rope at an angle of 90 degrees.

#### Step 4. Change the length

Find out what happens to the velocities of two pendulums of different lengths. Count the time to see if the shorter pendulum moves faster or is the same as the longer one.

## Tips

• Don't use anything fragile or valuable as a ballast, as it could break.
• Keep the pendulum string longer than the diameter of the ballast.