Rocket Car

TOPIC: Newton's Third Law of Motion

OBJECTIVE: To construct a car to demonstrate how rockets move by means of action and reaction.

DESCRIPTION: A small car is propelled by the action/reaction force generated by a balloon.


EDITED BY: Roger Storm, NASA Lewis Research Center



  1. Using the ruler, marker, and drawing compass, draw a rectangle 3 by 7 inches and four circles 3 inches in diameter on the flat surface of the meat tray. Cut out each piece. Use an emery board to make the wheels as round as possible.
  2. Push one pin into the center of each circle and then into the edge of the rectangle as shown in the picture. The pins become axles for the wheels. Do not push the pins in snugly because the wheels have to rotate freely. Test them to be sure they rotate freely. It is okay if the wheels wobble.
  3. Inflate the balloon a few times to stretch it out a bit. Slip the nozzle over the end of the flexi-straw nearest the bend. Secure the nozzle to the straw with tape and seal it tight so that the balloon can be inflated by blowing through the straw.
  4. Tape the straw to the car as shown in the picture.
  5. Inflate the balloon and pinch the straw to hold in the air. Set the car on a smooth surface and release the straw.

DISCUSSION: The rocket car is propelled along the floor according to the principle stated in Isaac Newton's third law of motion. "For every action there is an opposite and equal reaction." The balloon pushes on the air and the air pushes back on the balloon. Because the balloon is attached to the car, the car is pulled along by the balloon.


Aerospace Education
Services Project
 Oklahoma State University