Spinning Penny

Spinning Penny

Keep the little ones amazed for hours with this quick and simple lesson on centripetal force! Beware! This project is incredibly fun, makes a little bit of a ruckus, and is incredibly mesmerizing! 

5 - 8
Est. Time:
<30 mins

How we did it:

Materials List

  1. balloon (1)
  2. penny (1)
  3. hex nut (1)
  1. All you need for this experiment is a balloon (clear works best so you can see the object spin) and a round object. We tested this with both a penny and a hex nut.

  2. Place your round object of choice through the mouth of the deflated balloon Hold your balloon up and give it a shake to make sure it's all the way into the body of the balloon. This is so that there is no risk of the object being inhaled while blowing up the balloon. (We recommend an adult to blow up the balloon.)

  3. Inflate the balloon and tie it with a simple overhand knot.

    Move the balloon in a tight circular motion to get the object inside spinning. Can you get it moving fast enough for the penny to start to climb the walls of the balloon? How long does it spin after you stop moving the balloon? What kinds of sounds are you hearing? We tried this experiment with both a penny and a hex nut the hex nut made the coolest sounds! You can also try out other small objects to see what they look and sound like!

  4. So why does the penny climb up the inside of the balloon? Spinning the penny in a circle causes it to press outwards, against the walls of the balloon. (If you've ever gone on a carnival ride that spins in a circle, you've experienced what this feels like.)  This push allows the penny to stick to the sides of the balloon, seemingly defying gravity!