Materials:
A couple of Styrofoam trays (typically about 8″ x 6″; ask the butcher at your supermarket for them)
Template: click here to download
Permanent marker
Scissors and tape
Balloon (any size, but the bigger it is, the farther the car will travel)
Bendy straw (any size)
Straight pins (about 1 1/4″ long)
Steps:
- Use the template to trace and cut out 1 rectangle, 4 wheels, and 4 smaller hubcaps from the Styrofoam trays.
- Blow up the balloon, then let the air out to make it easier to blow up later.
- Tape the opening of the balloon around the short end of the flexible straw so that no air can escape; you’ll still be able to inflate it by blowing into the straw.
- Tape the long end of the straw down the middle of the rectangle with the open tip hanging off the back.
- Push the pins through the center of the hubcaps, then into the center of the wheels, and then into the edges of the rectangle. Leave a tiny bit of space between each to be sure the wheels can rotate.
- Blow up the balloon through the straw and then pinch the end of the straw closed.
- Place the car on the floor and let it go!
Why?:
As the air leaves the balloon in one direction, it propels the car forward in the opposite direction. This illustrates Newton’s Third Law of Motion: Every action (in this case the air escaping out through the straw) has an equal and opposite reaction (the car moves across the room in the other direction)