For Kids

Science Experiment: Centripetal Force - Hex Nut Balloon


Explore Forces and Motion


Have you ever put a coin in one of those wishing wells that is shaped like a giant funnel? The coin rolls around and around the sides of the funnel in smaller and smaller circles until it goes down the hole in the middle of the well? That coin is demonstrating centripetal force. Centripetal force is the force that pulls a thing toward the center of the little whirlpool that forms when you drain the bathtub or like the Zinga water slide at Holiday World! Why IS that water slide called Zinga? Because in Swahili Zinga means “to move in a circular motion”. Lots of amusement park rides work because of the laws of physics.

You can use a balloon to demonstrate centripetal force.

What You Need:

  • Balloon
  • Hex Nut

Blow up a large balloon. Before you close the balloon, put a hex nut in it and then tie the end of the balloon closed. Hold the balloon between your hands and move it in a circular motion until the hex nut starts to roll around the inside of the balloon. Now stop moving the balloon and watch what happens to the hex nut. What you are seeing is centripetal force. The hex nut is on a circular path inside the balloon. Things that are moving in a curved or circular motion will slowly move toward the center of the circle, in this case, the bottom of the balloon. What sound does the hex nut make? How about a penny? A marble? Try them all and see how they behave the same or differently.

Websites, Activities, Printables:

Science in ContextScience in Context: Centripetal Force 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 centripetal force.


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.


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