Hovering Hot Air Balloons
This flying experiment is awesome indoors and outdoors. You use helium balloons, ribbon and foam cups to simulate hot air balloon flight. Students add and subtract weight to get their hot air balloon to hover and travel around.
Helium Balloon with 6-10 foot ribbon attached * 8 ounce foam cup * Crayons and/or markers
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1. Decorate your cup and make it look beautiful.
2. Use a pencil or pen to punch 2 parallel holes (one on each side of the cup) just below the rim.
3. String the balloon ribbon between the two holes and pull it through until the balloon is about 1.5 feet from the cup.
4. Tie the ribbon onto the tied balloon opening so that the cup appears secured to the balloon on two sides. There should be several feet of ribbon as a leash attached to the tied end of the balloon.
5. Add and subtract weight to get the balloon to hover at one level. Gently blow on it to get it to travel around the room or the yard.
6. You can park your balloon by putting heavier weights in it.
How to present it to your group:
1. Create a sample hot-air balloon by decorating a cup to look like an old fashion basket complete with furnace and people. You will need your sample when explaining what is going to happen.
2. Talk about how hot air balloons rise by having the tem- perature of the air in the balloon warmer than the air around it. Explain how the balloon operator would cre- ate warm air to get the balloon to rise and then attempt to hover and travel on air currents.
3. Be specific explaining how they can first figure out just the right weight to get the balloon to hover (stay at one level). As they travel around the room or yard they will notice that air temperature changes and will affect their balloon differently.
4. Start the activity indoors so students get the hang of hovering and controlling their balloons. After a while you can bring the activity outdoors.
5. Be sure to secure strings/ribbons to the studentís wrists when they are outdoors. Have some extra balloons to replace the inevitable escapee.
6. Outdoors, we have enjoyed adding ribbon, yarn or string and extending the length of the leash. Flying a balloon with a 20-foot leash is quite different from flying with a 6-foot leash. Have fun experimenting with different lengths.
Hot air rises because it is lighter (less dense) than colder air. Helium is lighter than air and a helium balloon acts much the
same as a balloon full of hot air would in our hot air balloon experiment. The buoyant force of the helium causes it to rise in the lighter air. The buoyant force is neutralized by adding weight to the balloon basket (foam cup) reminding us of the force of gravitational pull.
The preschool lesson is in adding objects to the cup to control the rise of the balloon. Start by attaching foam cups to a few balloons. Divide your children into groups of 2-4 who will work well together. Have each group add or subtract weight to the cup to get their balloon to hover.
This activity will last 15-25 minutes indoors or out.
Weight of air, buoyant force, gravitational pull, balance, density