There’s no reason to wait for Halloween for this creepy STEM activity. Kindergarten kids can make their own screaming pumpkin balloons within seconds. Older kids may have just as much fun with screaming ghost balloons or creating their own screaming monster balloons.
- 7” or 12” Balloons. White balloons for ghosts; orange balloons for pumpkins, and any color for monsters. Clear balloons show the effect of the spinning objects inside.
- A hex nut for each balloon. Smaller hex nuts make higher pitching sounds.
- Permanent Marker to draw on the balloon or stick on paper eyes.
- Penny and marbles (optional to demonstrate spinning but no sound)
What Mystery Are We Solving?
What is the science of sound mystery that causes the balloon to scream when you add a hex nut but a penny will spin without making a sound?
There’s nothing particularly dangerous about this experiment. Have an adult present to help and use common sense to prevent toddlers from swallowing balloons.
Make sure the hex nut isn’t stuck at the mouth of the balloon. When blowing it up it may pop out a person may accidentally swallow it.
- Place a hex nut inside the deflated balloon. Be careful not to punch a hole in the balloon. Push the hex nut all the way through the mouth into the balloon.
- Blow up the balloon up to 6 to 8 inches. Avoid overinflating the balloon to prevent it from bursting. Tie the balloon.
- Draw with the permanent marker the ghost or monster face on the balloon. Alternatively, draw the eyes on a piece of paper and stick it onto the balloon.
- Hold the top of the balloon with your fingers down the side of the balloon.
- With your palm down twirl the balloon in a circular motion.
- Sometimes it takes a few tries to get the hang of it. When the hex nut stops bouncing around and begins to roll around in the balloon, the screaming starts.
- Hold the balloon steady with your other hand while the hex nut spins inside it for about 10 seconds.
- Use a clear balloon to insert a penny and see how it spins without making a sound.
What Just Happened Here?
The shape of the balloon forces the hex nut in a circular motion instead of linear motion. The centripetal force acts on the hex nut to keep it moving in a circle and is directed toward the center of which it’s moving.
The six flat sides of the hex nut crash against the sides of the balloon and bounce away. It causes vibrations that result in the screaming sound. The round penny will spin but doesn’t cause the sound vibrations as a six-sided object does.
The hex nut movement is unhindered because there’s very little friction between the balloon sides and the hex nut takes a while before it slows down and stops. It is a great example of Newton’s first law of physics. The penny or hex nut stayed in motion until gravity acts on it.