Grapes, good golly!

Hey guys!
We hope you've been enjoying the summer. We figure you might have hit a lull in activity, so thought we'd see if we could help. We found a couple of things to try at home, just ask an adult for permission first, and have a "grape" time!

Sparking Grapes

You need:
White grapes
Knife
Microwave-safe plate
Microwave oven

1. Slice the grape down the center toward the stem, but not all the way through. The two halves should just be attached by a tiny piece of grape skin.
2. Place the two grape halves face down on the plate.
3. Set the microwave for 20 seconds. Turn it on and watch the sparks fly.

What happened? The oven produces microwaves, which are a type of electromagnetic radiation. All electromagnetic waves create a changing electric field, which will cause electrons to move. (Electrons are negatively charged particles located around the nucleus of the atom and everything in the world is made up of atoms, so everything has electrons.) Moving electrons through a thin conductor will give you light just like a filament in a light bulb. In this activity the thin flap of grape left is a conductor, and the microwaves make electrons move through it.

It's Not a Shoe Box! It's a Catapult!

You Need:
Duct or packing tape
Long plastic spoon
Shoebox
Rubber bands
Grapes (or any small item)
Outdoor area

1. Tape the bottom of the spoon to the end of a shoebox. The concave part of the spoon should face along the side of the box.
2. Loop one end of the rubber band around the spoon and tape the rubber band to the middle of the spoon. Tape the other end of the rubber band to the side of the shoebox. Make sure you've got a good stretch on your rubber band, so there's tension. (To increase tension, use a smaller rubber band, or loop it around the spoon a couple of times.)
3. Use one hand to hold the shoebox. Use the other hand to load the grape on the spoon and pull back on the spoon. Let it go and launch the grape. How far did it go?
4. Adjust the position of the rubber band so it stretches farther, creating greater tension. How does this change the launch? What happens if you use more than one rubber band?

What's going on? Whether they're built to launch grapes at targets or boulders at castle walls, all catapults work because of elastic materials. Here you're using the elasticity of the rubber band to store energy in your catapult. You put the energy in your catapult. You put the energy in the rubber band by pulling the spoon back with your hand. That energy goes into the grape and becomes kinetic energy. So the grape flies!

ideas from Smash It! Crash It! Launch It! 50 Mind-Blowing Eye-Popping Science Experiments