Science Experiment: Momentum – Pendulums

Science Experiment: Momentum – Pendulums

A pendulum is a weight hanging from a fixed point. A yo-yo on a string can be a pendulum if you have ahold of the string and hold it in one place while the yo-yo hangs down freely. Pendulums are also associated with clocks or hypnotists, who swing an object back and forth from a fixed point. On a swing, YOU are a pendulum. Pendulums are affected by laws of motion. When a pendulum swings it has momentum. In this video, Bill Nye the Science Guy demonstrates momentum:

Things You Need:

• String 3 feet long
• 2 Strings 2 feet long
• Two Mugs
• Two Chairs
• Scissors

This experiment will show you something surprising about how momentum works. Set two chairs back to back about 3 feet apart. Tie a piece of string to the back of one chair and toe the other end to the back of the other chair. The string should not have a lot of slack in it. Tie a 1 foot long piece of string to the piece of string suspended between the two chairs about 18 inches from one of the chair backs. Now tie the other 1 foot piece of string to the suspended string about 18 inches from the OTHER chair back. When you are done, the two pieces of string should be a about 1 foot apart. Now tie a mug to the end of each dangling piece of string. Pull back on one mug and let go, letting it swing back and forth until it stops. Does it stop? What does the other mug do? When you release the first mug, momentum keeps the mug swinging back and forth. The mug will swing until friction in the air and friction from the string knot rubbing on the handle slows it down.

The weird thing is that when the first mug slows down…the second mug will START swinging, even though you never touched it! Some energy from the first mug travels along the string and makes the OTHER mug start swinging. Even though the momentum of the swinging mugs is slowed down by friction, some of the energy is transferred to the string, which carries it to the second mug.

Science Project Idea: Replace the mugs in this experiment with matching objects of different weight. Try two matching plastic mugs. How much momentum do the plastic mugs have? Does the momentum from a plastic mug have enough energy to pass through the string to the second plastic mug? Try hanging two metal forks from the string. Now try two plastic forks. Which kinds of objects have enough momentum to transfer energy to the second object without even touching it?

Websites and Databases for Research:

Science in Context: Momentum is a database you can use in any IndyPL Library Branch or at home. Login using your IndyPL library card number. The Science in Context database will show you articles, images and videos to help you learn about momentum.​

You can also ask a math and science expert for homework help by calling the Ask Rose Homework Hotline. They provide FREE math and science homework help to Indiana students in grades 6-12.

Books:

Use your indyPL Library Card to check out books at any of our locations, or check out e-books and e-audiobooks from home right to your device. Click on a book jacket below to request a book or download it. Need help? Call or ask a Library staff member at any of our locations, text a librarian at 317 333-6877, or leave a comment.

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