Catapults: The Old Heave-Ho

 

      Today's Snack: Have a bowl of grapes, and try this - though be sure to clean up if you spill anything. And if you can't do it, don't keep trying or you'll waste food. Place a spoon on the end of the table, and place one grape in the bowl of the spoon. Push it so that it's as far away from the edge of the table as possible, with still a little of the spoon's handle resting on the table, with your thumb holding it in place. Now, keep that thumb holding the spoon's handle in place. Then, with the other thumb, briefly push down on the bowl of the spoon, and then let go again so that it snaps. The grape should be catapulted up into the air, and here's the tricky part - catch it in your mouth! If you can do it, you can catapult the whole bowl of grapes, but if you miss more than one, you have to give up and just eat your grapes the non-catapult way.

 

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Supplies:

 

Plastic or wooden rulers

2' section of lath (thin, narrow, flat piece of wood for a lattice; buy at hardware store)

Large-size craft sticks

Can of soup, unopened but label removed

Full plastic liter bottle (refilled with water OK, but needs a lid)

Round wastebasket or bucket

Cardboard tube

Marker pen

Duct tape or masking tape

Five newspaper pages

Five different sizes of containers

Measuring tape

 

 

            A "catapult" is like a mechanical slingshot. It's a device that makes something move very quickly. Centuries ago, military armies built and used catapults to hurt big stones and arrows at enemy castles. Catapults can get things into the air in a hurry and make them go farther than you could throw them. But catapults take skill to make a use.

 

            Let's build a simple catapult in the style of a playground teeter-totter, or seesaw.

 

            First, tape a ruler or other flat stick, such as a lath or large craft stick, securely onto a sturdy cylinder, such as a soup can.

 

            Experiment with different types and sizes of these two basic elements - the long, flat stick and the round, sturdy cylinder - to see what happens when you change the weight, length and width of either part.

 

For instance, what if you used a cardboard paper towel tube instead of a soup can? Would your flat part collapse it? Do you think the catapult would still work?

 

What if you used a three-foot section of lath instead of a two-foot section? How would you have to change the cylinder, or would you have to?

 

What if you used a full liter bottle instead of the soup can? Would your flat part be able to "spring" the payload (that's the thing that you're going to catapult away) if the cylinder is so wide?

 

            You might even try to rig up a "trigger" that swings at the payload to catapult it up into the air.

 

            To make a payload, squash five newspaper pages into balls about two inches wide. Tape into a ball shape.

 

            Experiment with catapulting to see how much force you can use to vary the arc and the distance of the payload. When you do it slowly and gently, how far does the newspaper ball fly? If you give it a forceful karate chop, how far does it fly?

 

Now you have your catapult and your payload, so it's time to set up your targets. You should have five empty, clean containers of different sizes. Examples: laundry basket, small wastebasket, lidless shoebox, empty margarine tub and an empty metal can. Set up those five containers in an area that is five feet wide and five feet long. You can measure the area out and mark it with masking tape.

 

            Decide which target will be the toughest to catapult a newspaper ball into. Assign it 50 points. Choose the next-toughest; it gets 40 points. Assign 30, 20 and 10 points for the remaining three containers.

 

            Mark a "foul line" about five feet away from the closest container. After you get started, if that's too far away and you're having trouble scoring, you can dispense with the foul line and get your catapult right up next to the five-foot square tape to send your shots.

 

            Now set up your catapult on the floor, place a newspaper ball on the payload end, take aim, and fire. You can try to get all five in the toughest target, or all five in the easiest target, or just close your eyes and hope for luck.

 

            If you don't like your score, "redesign" your catapult, and try again!