A balloon-powered car is powered by the air released in the straw. One must blow into the straw which inflates the balloon. When you blow up the balloon, set your racer down, and let it go, escaping air from the balloon rushes out of the straw causing propulsion. The principle at work is Newton’s Third Law of Motion, which states that for every action, there is an equal and opposite reaction. In the case of the Balloon Powered Car, the action is the air rushing from the straw. The reaction is the movement of the car! The moving Balloon Powered Car has kinetic energy, but even an object that isn’t moving has energy. This energy is called potential energy. The potential energy of the car is in the elastic material of the balloon. As the balloon fills with air, it builds more potential energy. As the air flows from the balloon, it changes to kinetic energy. This is the conservation of energy.
Using the old mousetrap car base and wheels, we will investigate how the diameter of the balloon correlates to the distance the car goes. Hypothesis: If we increase the diameter of the balloon, then we will expect a greater distance. Independent variable: The different diameters of the balloon measured in centimeters. Dependent variable: The distance the balloon-powered car will go in centimeters. Controls: Surface (smooth tile), Temperature (to keep constant kinetic energy inside the balloon), Unit of measurement (centimeters), Wheels (rubber), Position (facing forward) Unit of Measurement: Centimeters
1)Take out the mousetrap in the old mousetrap car and keep the base and wheels. Those will be used as the base and wheels of your balloon-powered care. 2)Cut the mouth ring (the lip that you blow into) off of the balloon. This will allow for a better seal between the balloon and the straw. 3)Insert a straw approximately 1″ into the balloon. Use tape to securely fasten the straw inside the balloon. The tighter the seal, the better your straw is going to work, so make sure as little air as possible can escape. 4)Mount the straw so that the point where the straw and balloon connect is about 1″ from the end of your chassis. Taping it at this point is
your best bet. Secure the straw so that it points straight out from the chassis. 5)Inflate the balloon and pinch the straw to keep air inside the balloon. Place the racer on the ground and let it go! TrialsDiameter: 15 cmDiameter: 20 cmDiameter: 25 cm
1130.4 cm210.2 cm265.7 cm
2120.5 cm165.1 cm210.9 cm
3135.1 cm195.0 cm235.4 cm
Diameter: 15 cmDiameter: 20 cmDiameter: 25 cm
Average distance:128.7 cm190.1 cm237.3 cm
Exact measurement of balloon with ruler
Precise alignment with the tiles
Exact measurement of distance with ruler
Resuming trials the next day
Through our data that we recorded, we have concluded that there is a direct proportion between the diameter of the balloon and the distance of the car. Our hypothesis was correct; if you increase the diameter of the balloon then the distance of the car will increase. This is because the more air inside the balloon will result in more air being released resulting in a greater force pushing the balloon forward. There were systematic errors in our trials with the measurements of the balloon diameter and the distance. Also, the resuming of the trials the next day may have caused a slight temperature change causing the volume of the balloon to differ from the day before. Also, there were random errors with our placement of the car along the tiles, and the ability of the wheels to spin as they should. Another slight error might be the weariness of the balloon over time and how quickly the balloon would be able to spit out air out of the balloon after each trial. Also, after measuring, as we pinched the straw to hold the air inside the balloon some air may have left the straw causing the balloon to decrease it’s diameter.