Watermelon pop : Fizzics Education

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# Watermelon pop

### You will need:

• A full-size watermelon
• Ruber bands that will fit around the watermelon (we used 87 x 6mm rubber bands)
• Option: A platform to raise the watermelon up
• Safety glasses
• A hose to clean up
• People eat the leftover watermelon!

1

Put your safety glasses on. Stretch a rubber band around your watermelon.

2

As you add more and more rubber bands you’ll find that they will tend to spread out around the watermelon rather stay in the centre. Try to keep as many of the bands around the middle of the watermelon as possible.

3

You may find it easier with two people stretching multiple rubber bands over the watermelon to speed up the process. As soon as you see the watermelon begin to split, it’s time to step back!

The photo above was taken at the exact moment the watermelon started to split

4

Once the watermelon has begun to split it will likely implode at any moment. The image above was taken roughly 4 seconds after the first split was seen in the previous step!

5

#### Get the Unit of Work on Forces here!

• Push, pull
• Friction & spin!

From inertia to centripetal force, this unit covers many concepts about Newton’s Laws!

Includes cross-curricular teaching ideas, student quizzes, a sample marking rubric, scope & sequences & more

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### Why does this work?

It’s all about stored energy and applied force!

When you stretch rubber band, you store potential energy that can be released as kinetic (moving energy). The watermelon has a thick rind, as such, it can resist the force from many rubber bands. If you concentrate the force of the contracting rubber bands into the same area of the watermelon, eventually the force overcomes the resistance of the watermelon rind and the watermelon implodes… releasing all of the stored potential energy into a dramatic kinetic explosion of watermelon!

### Variables to test

• Try thin vs. thick rubber bands.
• Is there any difference if the watermelon is warm vs. cold?
• What about different size or types of watermelon?

### Want another potential to kinetic energy experiment?

Try creating a Cobra weave!