Applied Science - Technology (6A)
Pre Lab 

   
OBJECTIVES:
  • Exploring principles used in the aeronautic industry.
  • Investigating Bernoulli's Principle.

VOCABULARY:

  • lift
  • pressure
  • velocity
MATERIALS:
  • strip of paper, book

Students use a worksheet to investigate Bernoulli's Principle.

BACKGROUND:

Bernoulli is the name of a Swiss family of famous scientists and mathematicians, from 1650's to 1790's. Daniel Bernoulli (1700-1782) was the most famous. He was a doctor, mathematician, professor of botany, anatomy and natural philosophy. His most important work was Hydrodynamica dealing with the theory of statics and motion of fluids, the subject of this pre-lab.

The forces that lift an airplane and hold it up, are due in part to the air that flows swiftly over and under its wings.

Make a wing by placing one end of the strip of paper between the pages of the book so the other end hangs over the top of the book as shown in the diagram on the right. Move the book swiftly through the air, or blow across the top of the strip of paper. It flutters upward.

It doesn't matter whether you move the air over the strip of paper by blowing or whether you move the paper rapidly through the air, either way it rises.

Bernoulli's Principle states that an increase in the velocity of any fluid is always accompanied by a decrease in pressure. Air is a fluid. If you can cause the air to move rapidly on one side of a surface, the pressure on that side of the surface is less than that on its other side.

PROCEDURE:
  1. Draw the following picture on the board.

  1. Bernoulli's principle works with an airplane wing. In motion, air divides at the leading edge of the wing. Some of the air moves under the wing, and some of it goes over the top. The air moving over the top of the curved wing must travel farther to reach the back of the wing, consequently it must travel faster than the air moving under the wing, to reach the trailing edge (back edge) at the same time. Therefore, the air pressure on top of the wing is less than that on the bottom of the wing.
      
  2. On the worksheets, students determine where the higher and lower pressures can be found. Instruct students to put a H for high pressure and L for low pressure on each of the diagrams.
      
  3. Answers

 

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