This week we are building catapults using a simple machine: a lever. Here are the materials you need to make one at home:
yardstick
1 and 1/2" PVC pipe (approx. 3" section)
rubber band (optional)
dixie cup
ping pong ball
The yardstick serves as the "lever" and the PVC pipe serves as the "fulcrum." Place the PVC pipe under one end of the yardstick. String the rubber band through the middle of the PVC pipe, then wrap each end around the end of the yardstick to attach the PVC pipe to it. Then slide it down toward the middle of the yardstick. (You don't really need the rubber band, but its purpose is to help keep the fulcrum in place as you use the lever. Just slide the rubber band with the fulcrum back and forth down the yardstick to adjust the placement of the fulcrum.)
Use a glue gun or strong tape to attach the dixie cup, open side up, to one end of the yardstick. Now the fulcrum (PVC pipe) should be on the underside of the yardstick and the dixie cup should be on the top. This is for holding the ping pong ball.
Now you're ready to play! When you put the ping pong ball in the dixie cup, that is called the "load." Use your hand or foot to push down quickly on the other side of the yardstick (this is called the "effort") and see how far your ping pong ball flies through the air!
Practice placing the fulcrum at different locations along the yardstick to see how that changes the distance your ping pong ball travels. What is the best placement for the fulcrum?
