Catapults: The Old
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.
Plastic or wooden
2' section of lath (thin,
narrow, flat piece of wood for a lattice; buy at hardware store)
Can of soup, unopened
but label removed
Full plastic liter
bottle (refilled with water OK, but needs a lid)
Round wastebasket or
Duct tape or masking
Five newspaper pages
Five different sizes
"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.
build a simple catapult in the style of a playground teeter-totter, or seesaw.
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.
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?
might even try to rig up a "trigger" that swings at the payload to catapult it
up into the air.
make a payload, squash five newspaper pages into balls about two inches wide.
Tape into a ball shape.
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.
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.
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.
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.
you don't like your score, "redesign" your catapult, and try again!