# Balloon Powered Car

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Your balloon powered car demonstrates Newton's 3rd law of motion. Newton's third law states that every action has an equal and opposite reaction. When the air from the balloon goes through the straw, it carries a force. The direction of this force is in the direction of the flow of the air, in your case, to the back of the car. This is force is 'action'. According to Newton's 3rd law, there should be an equal and opposite reaction. The reaction force will then work opposite of the air flow, meaning towards front of the car. This force will cause the car to move forward. So you see, Newton's 3rd law can explain your balloon powered car. air shoots out the back at high speed and the car moves forwards (more or less) at low speed. So the force used to accelerate all that air backwards has an opposite force on the balloon (reaction) which is tied to the car so pushes in the opposite direction. Well the air's coming out fast in the beginning but thats when the car is only just moving, it takes a while to speed up and it takes even longer if you have a heavy car. So you may be able to argue it shows that f is proportional to Mass x acceleration (but to be honest I think that would be stronging it a bit - balloons don't seem to give very constant thrust. First, you have to know the 3 laws of motion. 1."A body continues to maintain its state of rest or of uniform motion unless acted upon by an external unbalanced force." 2."F = ma: the net force on an object is equal to the mass of the object multiplied by its acceleration." 3."To every action there is an equal and opposite reaction." To prove the 1st law, you can see that the air released from the balloon disturbs the state of rest of the car and makes it move. To prove the 2nd law, you need the exact measurements, so I can't help you. To prove the 3rd law, you can see that as the air in the balloon is