# Science Project: Balloon Rocket Car

Jun 07, 2012

Never thought you could do rocket science? Well, think again! This project uses the basic principles that send rockets into our solar system. You won’t need jet fuel though, just a balloon. Learn how to make Rocket Balloon Cars!

## Rocket Science

In its simplest form a rocket is a chamber that contains a pressurized gas and a small opening, called a nozzle, in that chamber which releases the pressure. The force of the released, which is called thrust, pushes the rocket in the opposite direction of the thrust. The best way to think of it is how a skateboard moves. You push back on the ground to push the skateboard forward. This principle of motion is one of Sir Isaac Newton's 3 Laws of Motion. In fact, it's the 3rd: for every action there is an equal and opposite reaction. Now, knowing all the science behind it, you're ready to make your car!

Materials:

• Balloon
• Rubber Band
• 4 bottle tops (all the same size for the wheels)
• 1 nail
• Hammer
• Cardboard (6 inches by 4 inches)
• 2 wooden skewers
• 2 straight straws
• 1 bendy straw
• Tape

Procedure:

1. Take the piece of cardboard and tape the two straight straws to it, one on each of the narrower ends. Place them where you think the two wheels should go so that the car is balanced. Think of where car wheels are under the body of a car.
2. Take your bottle caps and using the nail and hammer poke holes in the center of each plastic disk. You may want to get some experienced help with this one, because it can get tricky.
3. Take your two wooden skewers and poke one end of the skewer into one of the bottle caps. Thread the other end of the skewer through the straw attached to your cardboard. Poke the other bottle cap through the other end of the skewer. ***It’s important to remember to put the caps on so that the flat end, rather than the open end, is closest to the piece of cardboard. Otherwise the raised ridges of the open end will catch on the car and slow you down.
4. Repeat step 3 with the other set of wheels. Once that’s done spend some time adjusting the wheels and axles are straight, this will make the car go faster!
5. Take your bendy straw and fold the bend so that the two ends of the straw are parallel to each other. Cut the longer end of the straw so that you have an elbow of straw with two sides the same length.
6. Stick one end of the straw elbow into the neck of the balloon. Take your rubber band and secure the straw in the balloon. Wrap it as many times as will make it tight, but will still allow air into the balloon.
7. Place the balloon on your cardboard car and make sure that the straw is extended over the edge of the car. This will make it easier to blow up the balloon. Tape it to the car.
8. Blow up the balloon and hold the straw closed so that air doesn’t escape. Find a nice long runway for your car and let her rip!

## Science Project

To make your rocket go faster you can increase the size of the nozzle, where the air escapes the balloon. In this model your nozzle is the size of one drinking straw. What if you used two or three? Or maybe you can think of something else, like a piece of tubing. Get creative! Vary the size of the nozzle and record the different speeds and distances your car travels. This will surely get you a prize in the science fair.