February 8

A Fun Homeschool Science Experiment in Aerodynamics – Hot Air Balloon


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If you have ever noticed a bird flying, you will see how it uses its inherent ability to rightly use the aerodynamic forces to fly high in the sky as well as glide through the clouds tirelessly and effortlessly. I use these principles in a myriad of exciting homeschool science experiments, some of which I will share below.

These 4 aerodynamic forces are thrust (the force that makes a bird move forward), drag (the force of resistance which the bird has to minimize), lift (the force that makes the bird rise high) and gravity (the force that pulls the bird down). A slight imbalance in the above- and the flight would not be as graceful.

It is important to note that the force of lift and thrust is generated when the birds flap their wings. They also create a lift while gliding against a current of wind by tilting the front edges of the wings to create a difference in air pressure. Drag is minimized by the aerodynamic shape of the bird's body. Also, birds have hollow bones, making them lighter and reducing the effects of gravity. I will share some of my favorite homeschool science experiments below to demonstrate how objects rise in the air and why flying objects must be light in weight.

Airplanes and rockets are designed with these principles in mind. One or more of the above mentioned forces are dominant depending on the function of the flying object. Even if you and I had wings, we wouldn't be able to fly since our bodies are not aerodynamically shaped and we are heavy.

Now that you have learned something about aerodynamics, let's have fun with a hot air balloon experiment. If you've ever been in a hot air balloon, you will notice that the pilot adjusts the burner in order to make the balloon go upwards and downwards. He also uses the winds, caused by a difference in air pressure, to move from place to place. Let's make our own hot air balloon using a garbage bag.

Hot Air Balloon Experiment: Open up a garbage bag and make the mouth very narrow using duct tape. Make sure to leave a small hole to fill-in hot air. Now run a hair dryer for a few seconds till it blows hot air and then fill the bag with hot air. Now switch off the hair dryer and let go of the bag. The bag begins to rise towards the ceiling, where it stays for some time.

Hot air has less density. This means that there are fewer air particles inside the hot air balloon as compared to the outside atmosphere. Therefore there is less air pressure inside the hot air balloon as compared to the outside air. This makes the balloon rise.

Tissue Parachutes: Take four pieces of thin strings or sewing thread of equal lengths. Tie the threads to the four corners of a tissue paper. Tie the free ends of the four strings to a piece of stick. Prepare many such parachutes with different weights attached. Now drop them one by one from a balcony. Notice how fast each one drops to the ground.

Do you now realize why it is important for birds and airplanes to be light in weight?
The free “Homeschool Parent's Guide to Teaching Science” is filled with great science experiments and activities. Get your copy by clicking the link below.

A great free resource for really cool science experiments and activities is the Homeschool Science Experiment Guide.

Another good homeschool resource for science ideas, experiments and activities, is the homeschool science blog (just click on the Blog link). Definitely worth bookmarking.

Have Fun!

About the Author Aurora Lipper has been teaching science to kids for over 10 years. She is also a mechanical engineer, university instructor, pilot, astronomer, a real live rocket scientist (You should see the lab in her basement!) and a mom. She has inspired thousands of kids with the fun and magic of science.


home school, homeschooling, science

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