Science Master Special – the Bernoulli effect (Flying)

Blowing through two pieces of paper results in the two pieces of paper coming together. The same can be done with two balloons. Hold two inflated balloons in front of your mouth and blow between them. You will be surprised.

The question is why does this happen? Bernoulli in 1782 looked at a similar phenomena using water and blood. He discovered that when blood  moved faster it applied less pressure on it’s surroundings. I have tried to illustrate this phenomena in the form of an animated GIF (there are some great free animated GIF builders online)

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As I have said before the air is FULL of particles/molecules which are so small you cannot see them. BUT you feel them all the time. Try running holding a great sheet of cardboard in front of you, feel the wind blowing on you. Air molecules are constantly banging into you and everything around you. This is normally called ‘air pressure’. It’s the push of air on you and the two pieces of paper that you might be holding in front of your mouth.

Bernoulli in his work found that if you increase the speed of the, already moving , molecules they hit things around them less frequently and therefore less push means less pressure. I have tried to illustrate this in the animation above.

In an aeroplane as it moves through the air that goes over the top of the wing speeds up compared to the air underneath the wing. Look at a cross section of the shape of a wing. The push of the air on the bottom of the wing is therefore greater than the push of the air on top of the wing. Thus lift.

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