All it takes is a little elastic to send a pom pom flying! Can you improve your aim with a bit of practice?
You will need
- Small pom poms (or cotton balls or crumpled up paper)
- Toilet paper roll
- Balloon
- Scissors
- Duct tape
- Paper
- Markers (optional)
Safety
Don’t shoot your cannon at people or pets!
What to do
Take a balloon and tie a knot in the end. Cut the top of the balloon off, taking about a centimetre off.
Take the large portion of the balloon and stretch the cut part over one end of the toilet paper roll as far as you can. Try to position the knot off-centre over the hole.
Use your duct tape to secure the balloon to the toilet paper roll.
Now let’s make some targets! Fold your paper in half, and then half again. Cut the paper along the fold lines into four equally sized rectangles.
Fold each of the smaller rectangles in half to make a standing target you can try to knock over with a pom pom. If you’d like, you can use your markers to draw a bull’s eye on each target.
Stand about a half a metre away from your targets. Make sure no one is near the targets.
Load one pom pom into the canon so that it touches the balloon in the back. We found it worked best to keep the cannon level with the table and the off-centre knot positioned closer to the table than to the ceiling.
Then, with one hand aiming the cannon, use the other hand to pull the knot of the balloon back. When you’re ready, let it go!
Try variations of steps 7 and 8 – what worked best to hit the targets?
What’s happening?
Your cannon fires pom poms just like a slingshot! And the most important cannon component is the elastic balloon. This balloon allows you to turn energy from your muscles into motion energy for your pom pom. How does it do it? Let’s trace where the energy comes from and where it goes.
First, your muscles use chemical energy (which you got from food) to stretch the balloon. This is just like stretching a spring – the spring wants to return to its original shape. Because of this, stretching the balloon stores energy. The more you stretch the balloon, the more energy it stores.
When you let go of the stretched balloon, it “springs” back to its original shape. This changes that stored energy into motion energy. When the balloon hits the pom pom, it gives plenty of this motion energy to the pom pom. And that’s why your pom pom goes flying!
Our pom-poms were a bit smaller than the tube, so they sat a bit below centre. Our cannons worked best when the balloon knot was also a bit below centre. This way, the knot hits the pom pom head-on. When everything lines up, the collision will shoot the pom-pom straight forward with lots of energy. All the better to knock over those targets!
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