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    Home / Science projects / Balloon Rocket Car + Video
    • Balloon Rocket Car + Video

      Balloon Rocket Car + Video

      Balloon Rocket Car

      click to watch videoA rocket is simply a chamber filled with pressurized gas. A small opening called a nozzle allows the air to escape, causing thrust that propels the rocket. You can demonstrate this when you blow up a balloon and let it go without tying it off. The balloon will fly through the air as all the air inside escapes.


      >> Watch our video to see a balloon rocket in action!

      Sir Isaac Newton laid the foundation for the modern science of rocketry near the end of the 17th century. Newton's Laws of Motion are essential to rocket flight. Here are two of them:

      1.  'Objects at rest will stay at rest and objects in motion will stay in motion in a straight line unless acted upon by an unbalanced force.' In other words, the forces pushing a rocket up must be stronger than the force of gravity pulling it down.
      2. 'For every action there is always an opposite and equal reaction.' When an action takes place, like gases escaping from the rocket, a reaction follows - the rocket rises in the air.

      The principles of rocketry apply to more than flying rockets - with this project you can make a 'rocket car' that is powered by pressurized gas (air in a balloon!). Adult supervision recommended.

      What You Need:

      • 16-20 oz. plastic water bottle
      • Drinking straws
      • Wooden shish-kabob skewers
      • 4 plastic bottle caps
      • Balloon
      • Duct tape or masking tape
      • Nail, hammer, knife, scissors

      What You Do:

      The water bottle forms the chassis, or body, of your balloon car. You can start by mounting the wheels on this body.

      • Stretch out a large balloon by blowing it up and then letting the air out of it a few times. Next, make a nozzle. The size of the nozzle is very important. If it is too small, the air can't escape with enough force to propel the car forward. If it is too big, the air will escape too fast and the car won't go very far. Create the nozzle by taping four drinking straws together. Insert the straws into the mouth of the balloon and seal the opening by wrapping a strip of duct tape around it several times.
      • To mount the balloon/nozzle on the car, use a knife to cut two perpendicular slits (to make an X) in the top of the car about 4' back from the mouth of the bottle, as shown in the illustration. Thread the nozzle through this opening and out through the mouth of the bottle. Leave about an inch of the nozzle sticking out of the mouth.
      • Find a hard surface, like a long table, linoleum floor, or sidewalk. Blow up the balloon through the straws at the mouth of the bottle. Pinch the base of the balloon to prevent the air from escaping too soon. Set the car down, let go of the balloon, and watch it go!

      What Happened:

      The air in the balloon is gas under pressure. The air pushes against the balloon, causing it to expand, but the balloon is also pushing back on the air. The pressure of the balloon pushes the air right out through the nozzle, which creates thrust that propels the car forward.

      Keep track of how long the car rolls and how far it goes. Try it several times, then try changing the design to see if you can get it to go farther or faster. How will it work if you only use three straws for the nozzle? What if you use a bigger or smaller balloon? Does the car go farther on linoleum or the sidewalk? Why do you think this might be? Will the car go farther if you start it at the top of a ramp?

      Decorate your car and have races with siblings or friends. Try to figure out why one car goes faster or farther than another, and keep experimenting to make your design better!

      Film Canister Rocket

      Unlike a balloon rocket, most rockets create the gas they need for thrust via a chemical reaction. A fuel (like liquid hydrogen) is mixed with a source of oxygen (often liquid oxygen) and burned in a chemical reaction that produces a lot of gas! In this project you can make a simple rocket and fuel it by a chemical reaction that produces carbon dioxide. Make sure you launch this messy rocket outside!

      What You Need:

      • Clear film canister (the kind where the cap fits inside the canister, rather than over the outside. See if a local photography shop has any extras they can give you. )
      • Alka-Seltzer tablets
      • Water
      • Baking soda
      • Vinegar
      • A piece of paper
      • Cardstock or poster board
      • Tape

      What You Do:

      Overlap the paper at the slit to create a nose cone

      • The film canister is the engine of your rocket. Make a body for it out of the piece of paper. Line up the open bottom of the canister slightly below the bottom (short) edge of the paper, then tape the longer edge to the canister and start rolling to make a tube. Tape the tube closed.
      • Cut out four triangular fins and one nose cone from the cardstock. (To make the nose cone, cut out a circle, then make a slit from the outer edge to the center. Overlap the paper at the slit and tape it to create a cone shape.) Tape the fins and nose cone to your rocket.
      • Turn the rocket upside-down and fill the canister 1/4 full with water. Add half of an Alka-Seltzer tablet, snap the lid on, turn the rocket over and back away. 3-2-1 blast off!

      What Happened:

      The Alka-Seltzer reacts with water to produce carbon dioxide. When enough carbon dioxide is produced to create pressure on the inside of the canister, it will force the lid to pop off so the gas can escape. As the gas escapes the rocket is propelled upward.

      Try to measure how high your rocket goes compared to a nearby fence or a tree. Try it several times; do you get the same results each time? Does the rocket go higher if you add more or less water? Why do you think this is? What happens if you change the design of your fins or nose cone?

      Now try it again with a different type of fuel. When vinegar and baking soda are mixed together, they produce carbon dioxide. Experiment to see how much baking soda and vinegar will launch the rocket the highest. (Some tips: You can either pack the baking soda in the lid with a damp thumb so that the reaction doesn't start until you turn the rocket over, or you can wrap it in some tissue paper or toilet paper to delay the reaction starting and give you time to set the rocket right-side-up.)

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    By: anaya/jada
    Date: Jan 13, 2016

    me and my friend jada are making a balloon car for our science project. I think that this is a great rocket car and it goes really fast. That is what we need for the competition and we are looking forwards to or results. Although i have a question. Is there any way to customize this car so that it will be pretty.

    By: SC
    Date: Jan 06, 2016

    good description of how air can be used to propel an object forward. we will do this soon.

    By: Shahid Hanif Bhatbharde
    Date: Nov 27, 2015

    I like this vedio so much.
    Good job.It is awesome car.
    I also makes this ballon car.
    It is very speedy race car.
    It runs anywhere in the house.
    My mom and dad like this car so much.
    I gifted this car in my sister’s birthday.
    Thank you very much.
    Comment written by HAH.

    By: Gwen
    Date: Nov 18, 2015

    good job ( i guess )

    By: Georgia
    Date: Oct 16, 2015

    Can it carry a 200g weight??? It’s for a physics assignment and that is the only guideline.

    By: Gene
    Date: Oct 02, 2015

    Good project

    By: Pria
    Date: Sep 28, 2015

    This is sweet I used on project and helped me a ton

    By: jakayla
    Date: Sep 23, 2015

    the best project ever, it’s so awesome.

    By: Pravin
    Date: Sep 11, 2015

    Good job, v-good

    By: Manoj
    Date: Jun 12, 2015

    very nice balloon rocket car