BERNOULLI’S PRINCIPLE - Urban Steelworks



BERNOULLI’S PRINCIPLE

Bernoulli was a Swiss scientist who discovered how to make planes fly long before the first plane was built! What he discovered was this: the faster a fluid moves the less pressure it exerts. The Wright Brothers applied Bernoulli’s Principle to their airplane the Flyer I and earned their place in history by building the first successful flying machine!

Try this: Hold this paper in front of your face and right below your lips. Blow hard enough and the paper will do something strange.

Write what happens here: the paper lifts up

How does that happen? When you blow air across the top of the paper you are causing that air to move faster than the air below. So because air moving faster exerts less pressure than the slower moving air below, the paper lifts! This is exactly what happens with an airplane wing. The curve on the top of a airplane wing forces air on top of the wing to move faster so the wing is lifted by the greater pressure from below!

Draw how an airplane wing works below: (use page 91 in your textbook for help)

fast flowing air (air travels farther) → reduced pressure

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lift occurs due to slower flowing air → higher pressure

Now answer these questions from pages 89 – 92 in your book.

1. What year did the Wright Brothers successfully fly their airplane? Where did they fly

it? How long was the flight and how far did it go?

1903; Kitty Hawk; 12 seconds and 36 meters (just over 100 feet).

2. Write Bernoulli’s Principle. How is the pressure exerted by a fluid related to how fast

the fluid moves? Moving fluids exert less pressure. The faster the fluid the less the

pressure.

3. How does Bernoulli’s Principle explain how smoke rises in a chimney? How does a

spoiler work? What is the purpose of a spoiler?

Wind blowing across the chimney reduces pressure and smoke rises to fill

the vacuum.

4. How do bird wings demonstrate Bernoulli’s principle? Why is an airplane wing

curved? What is the purpose of the curve?

bird wings are curved like an airplane wing. Both are designed to force air over the

top of the wing to moved faster and reduce pressure thus producing lift.

5. How does an atomizer work? You can try this at home! Cut halfway through a straw

in the middle of the straw. Then put it in a glass of water and bend the straw at the

cut. Now blow through the straw and see what happens. Bernoulli’s Principle works!

An atomizer reduces pressure at the top of the tube allowing atmospheric pressure to

push the perfume up the tube

6. Bicycle racers sometimes draft, or ride right behind the rear wheel of a team member.

This allows them to ride as fast as the rider in front, but with less effort. Explain how

this works in terms of Bernoulli’s Principle.

rider in front reduces air pressure. rider in rear is pushed forward from air behind.

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