Safety: Wear Safety glasses and do not look directly over the watermelon as it is going to shoot up like a rocket!
This demonstrated show the difference between potential and kinetic energy by exploding a watermelon with rubber bands.
You will need a watermelon, 300-400 rubber bands, some Safety glasses and do this outside. Mom’s don’t think its funny doing this experiment indoors. : )
Put your melon on a table. We use a cardboard box to hold it up right. You will need two volunteers for the experiment as its little hard to pull the rubber band over the melon by your self. I would recommend one at a time start slipping rubber bands around it. You want to make a big belt of rubber bands around the melon’s middle, so just keep stacking them on top of each other.
We like to speed up the process by putting on 3 or 4 rubber bands at one time. I think get a better exploration this way.
After a few minutes of applying rubber bands, pause and take a look at your melon. Is it still the same shape? You may start to see the top and bottom of the melon bulge out around the rubber bands. It starts to look like the number 8 in the middle.
As we stretch the rubber bands out to get them around the melon. But once they’re in place, they start to contract, squeezing the melon. All that pressure from the outside is forcing the inside of the watermelon to find some place else to go, so it’s will start to bulge. Looks like the number 8 in the middle.
Rubber bands are a great example of potential energy. Potential energy is energy that is stored up, not being used, just waiting to be unleashed.
Think about when you stretch a rubber band, then let go and it snaps back. It’s using up its potential energy.
When potential energy is used up, it becomes kinetic energy—energy in motion. So right now all those rubber bands around the watermelon are stretched out and full of potential energy, ready to snap back. and guess whats going to happen to the melon in their way?
Keep adding rubber bands and eventually the strength of the rubber bands’ potential energy will put enough force on the watermelon to squeeze the top and bottom of the melon apart. The rubber bands will cut through the melon and contract. What do you expect the melon to do?
Once your melon explodes, the rubber bands will have snapped back and used up their potential energy for now.