SOS: The Science of Speed curriculum includes an excellent introductory activity (Zoon Air Car) for exploring Newton's third law of motion. More Tips

Thrust: Newton's Third Law of Motion

Sir Isaac Newton’s third law of motion states that for every action (or force) there is an equal reaction (or opposing force) in the opposite direction.

CO₂ cars are propelled by carbon dioxide rapidly escaping from a small container called a cartridge. The cartridge is positioned in the car so that the escaping gas moves in a rearward direction. The rearward force of the escaping gas is the initial action described by Newton.



The reaction part of Newton’s law is fulfilled by the car’s movement. Remember that the reaction occurs in the opposite direction: when gas escapes in a rearward direction, the car moves forward.

As the car begins to move, its resting inertia is overcome.