Make a car that is powered by balloon and moves on its own! This is a fun project that will test your science and engineering skills.
No. People: 1+
Age Group:
- Early Elementary, Middle School, Upper Elementary
Steps & Setup Instructions
- Cut two straws so they are slightly longer than the width of the bottle. Tape the straws to the bottle, making sure that they are parallel.
- Cut the skewers so they are slightly longer than the straws.
- Use the hobby knife to make small holes in the center of the four bottle caps.
- Push a skewer through one of the holes and push the bottle cap into the other end of the skewer. This makes an axle with two wheels. Repeat steps 3 and 4 to make a second axle.
- Make sure the axel spins freely and the car rolls smoothly. Adjust as needed.
- Slide the short end of the third straw into the neck of the baloon.
- Tightly wrap a rubber band around the neck of the balloon.
- Blow the balloon up through the straw to make sure there are no leaks.
- Cut a small hole (big enough for the straw) in the top of the car.
- Press the free end of the straw through the small hole and out the mouth of the bottle.
- Tape the straw so it points backwards, not down.
- Inflate your balloon and let the car go.
- You can hold the straw until you want the car to actually move.
- If the car does not move smoothly, try adjusting the wheels.
- Repeat blowing up the balloon and letting go of the car as many times as desired.
What's Happening?
- A balloon car is a great demonstration of all three of Newton’s laws of motion!
- Newton’s third law of motion states that for every action, there is an equal and opposite reaction. When the balloon deflates, escaping air is pushed out the back of the balloon. In turn, the air pushes the car forward.
- Newton’s second law of motion says that the net force acting on an object equals its mass times its acceleration. Acceleration is a change in velocity. You witness this as the car accelerates forward when the balloon deflates, and again as the car coasts to a stop (decelerates) when friction slows it down.
- Newton’s first law of motion states that an object in motion will remain in motion, and an object at rest will remain at rest, unless acted upon by an outside force. You may notice this is your car keeps moving even after the balloon has completely deflated. The car is already moving forward, so even though the balloon is no longer pushing it, it will keep moving until an outside force (friction) brings it to a stop.
- You can also think about this activity in terms of energy. When you inflate the balloon, it stores potential energy (in both the stretched rubber and the compressed air inside). When you release the balloon, this stored potential energy is converted to kinetic energy, the energy of motion. Eventually, the car will come to a stop, but the energy is not lost—it is converted to other forms like sound and heat (from friction). The total amount of energy is conserved.
Date added: 11/15/2023
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