Share it! Science : Flying and Twirling: Paper Toy Physics

## Tuesday, June 14, 2016

### Flying and Twirling: Paper Toy Physics

No doubt you've made a paper airplane before, but have you ever made an air spinner, flipping fish or twirling triangle? What else can you make fly through the air, and what makes these things move the way they do?

Physics for Kids: Lift

How does a plane stay in the air? You can do a simple activity to understand this physics concept. The reason airplanes and birds have lift is due to a concept called Bernoulli's principle.The air moving over an airplane's wing is moving faster than the air below it. When the air blows faster the air pressure decreases. The air pressure below the wing stays the same, therefore pushing the wing upward, or lifting it.
 image: www.quest.nasa.gov

You can demonstrate this by blowing on a strip of paper. Hold the narrow end of the strip of paper just below your bottom lip. Blow across the top of it. What happens?

Try it! A strip of copy paper 8 in long and 1 in wide works well.

Explore paper airplanes with the designs and directions here. Do some experiments. Maybe you can answer these questions:
• Which airplane designs have the most lift?
• Which airplane designs fly the furthest?
• What happens if you use construction paper or cardstock to build your airplane?
• What if you add some paperclips for weight?

The Science of Spin

There are all sorts of spinners and paper toys that fly that can very easily be constructed and tested. One of my favorites is this spinner (includes template). Once I made these with a group of preschoolers on a windy day and they went soaring right up and over the building! Add a paperclip on the bottom to improve your spin!

 My favorite spinners!

The effect here is the same as a helicopter's propellers, which is Bernoulli's principle again. A helicopter is different than an airplane in that it has a rotating propeller instead of wings. Instead of moving quickly forward to achieve lift, it has to use another method. When the propellers begin to rotate the air speeds up. Once all this air is circulating around the propellers, the air pressure changes and the helicopter can lift off.

You can find all sorts of designs for paper spinners in the "Air, Air Everywhere" section of the book Science Play! by Jill Frankel Hauser. Although this book is designed for ages 2-6, these paper designs can be enjoyed by any age. The designs for the "flipping fish" and a "twirling triangle" I mentioned earlier can be found here. You can experiment with different sizes and paper types. What happens when you add a little weight? The possibilities are endless!

Let's look at one of the designs from Science Play! here. This is the simplest design- the spinning bar.

Cut out a small strip of paper. Drop it, or toss it into the air. What makes it move this way? What other things move and spin as you drop them?

A maple seed comes to mind. These "helicopters" as we fondly refer to them, also called samaras, baffled scientists for years. The seeds spin when they fall through the air. They do so slowly to help them travel further away from their parent plant. How did they manage to stay airborne for so long?

In 2006 scientists discovered how a maple seed does its thing. The spinning causes a vortex, much like a tornado, that lowers the air pressure over the upper surface of the seed. Due to the shape of the seed, it is sucked upward, giving it twice as much lift as a non-swirling seed. In a sense the maple seed is using both the shape of an airplane wing and the rotation of a helicopter propeller to move. Nature, as usual, is pretty darn smart.

If you are fascinated by maple seed "helicopters" you should definitely check out Emily Morgan's book: Next Time You See a Maple Seed.

What else can you find in nature that spins in the air? We're excited to hear how your flying and twirling toy experiments go! Share in the comments or find us on Facebook, Twitter, or Google+.

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