Alien in My Pocket #5: Ohm vs. Amp (9 page)

H
ave you ever heard of the term
leverage
? As in, “We need to get a bit more leverage”? Zack cleverly uses a ball-throwing toy, usually used for chucking tennis balls for his dog, to get himself more leverage for throwing Ohm's ship into the air. You're probably already much more familiar with the concept of leverage than you think.

Levers are all around you. As Ohm points out in his note to the Erdian Council, a lever is basically a stick that pivots, or rotates, around a certain point. When we're thinking about the stick as a lever, rather than just a stick, we call that pivot point the
fulcrum.

The door to your bedroom is a lever. The fulcrum, or the point that the lever pivots around, is the pin going through the hinges of the door. A
teeter-totter on a playground is also a lever. Have you ever wondered what would happen if a really big person jumped onto the seat across from you? If the person were big enough, the teeter-totter might lever you right up into the air!

The Levers in Your Body

There are a few levers you use
every day
, even if you don't open a door or stop by the playground. Those levers are your arms and legs! Each joint—like your wrist joint or your shoulder joint—act as a
fulcrum
for those levers. Your hand and lower arm pivot around those joints, acting as levers.

The way the human body's levers are arranged make them very good for speedy movements because they're very long. Can you imagine if your end of the teeter-totter grew to double the length it started from? If a big kid jumped on the other end, you'd really go flying!

That's the same concept Zack takes advantage of when he uses his ball thrower to chuck Ohm's spaceship into the air. The ball thrower makes his arm—the lever that's throwing the ship—even
longer than it was to begin with, giving the spaceship an extra boost.

Ancient Leverage—the Atlatl

Humans have been using leverage to throw things extra far for a lot longer than tennis ball chuckers have been around. In fact, the first examples of intentionally using leverage for this purpose can be traced back to nearly 30,000 years ago! The most famous example, however, was used by the Aztecs in the sixteenth century, and is called an
atlatl
. It's a fantastic example of how a simple tool can augment human capability in a really powerful way.

You can build your own atlatl using a few simple materials.

YOU WILL NEED: Some pieces of cardboard a few feet long (ideally with the corrugations running lengthwise), a roll of tape (like duct tape), scissors, a stick about as long as your forearm, a pen to decorate the cardboard ship, a piece of dish sponge to serve as a soft tip, and an adult to help you cut the materials.

Making the Ship

       
1. Lay the cardboard lengthwise along a countertop or other flat surface with a corner edge. Use the edge to fold the cardboard along its length, with about a 1-inch width.

       
2. Fold the cardboard a few times until you can wrap the cardboard around on itself, making a long skinny tube. It can be a triangle, a square, or even rolled into a circle. It doesn't have to be a perfect shape, but it should be long, skinny, and pretty straight. Once you have wrapped the cardboard into a tube, have a grown-up help you cut off any extra cardboard. Use the tape to hold it in the shape of a tube.

       
3. Make fins to help the ship fly straight. In ancient times, creating fins with feathers, like on an arrow, was called fletching. We'll use more cardboard to make ours. You can choose how you shape your fins. Ask an adult to help you cut them. Definitely decorate them—maybe by drawing Ohm's face on one!

       
4. Then tape two fins to the bottom of the ship so they stick out evenly on both sides like wings of a plane. Tape another fin to the top of the ship so it appears to have three equally sized fins.

       
5. Cushion the front tip of the ship with something in case it hits anything delicate. You can use anything that's small and soft, but a piece of a dry, squishy kitchen sponge can work really well. With help from an adult, cut a little square out and tape it on the tip of the ship.

Building the Atlatl

       
1. Cut a small piece of cardboard in the shape that's shown in the picture. Cut it so that the cardboard can fold easily in half along one of the corrugation pieces. Fold the shape in half, and then tape it to the end of the stick.

       
2. If you can't find a stick the right size, you can make your own using the same technique you used to make the dart.

       
3. Tape the folded cardboard shape, or hook, onto the atlatl with one half of the hook on each side. Be sure to tape it tightly, and consider reinforcing it further with some tape. During a good throw, it's likely to undergo some high forces!

       
4. You might want to add a little grip on the bottom of your atlatl so it's easier to hold on to during a throw. You can tape a piece of cardboard onto the bottom of the atlatl, or make up your own grip enhancement.

Launching Ohm Back Home: Throwing with the Atlatl

       
1. Put the back end of the spaceship, where the fins are, into the atlatl's hook. Hang on to the atlatl's grip, and reach around the shaft with your thumb and fingers, using them to pinch the ship's long body and hold it in place parallel to the atlatl. You're ready to throw!

       
2. Throwing with the atlatl uses the same motion as throwing a baseball, so use exactly the same technique. The atlatl will naturally let go of the ship at the right time.