Unit Two What is the Bernoulli’s principle?

Before we get to know what the Bernoulli's Principle is, let us try two interesting experiments. Before you conduct each experiment, think about what the result will be and write it down. After you have finished the experiment, write down the actual result and think about why.

Activity1

Follow the steps below:

Step1:Hold two pieces of thin paper vertically a short distance apart.

Step2:Blow down into the space between them.

Step3:Write down your findings.

Activity2

Follow the steps below:

Step1:Hold one end of a small sheet of paper in both hands.

Step2:Keep the held edge horizontal while the other end sags under its own weight.

Step3:Blow steadily over the top of this horizontal edge.

Step4:Write down your findings.

Teaching notes

It seems amazing that the two sheets of paper move closer together in the activity1. In activity2, the lower end of the paper moves upwards slowly. In both cases, pressure is reduced where air is moving quickly. This is called the Bernoulli principle.

See more Bernoulli's principle experiments: https://www.youtube.com/watch?v=sIrJOrTAJjg

See more Bernoulli's principle definition: https://en.wikipedia.org/wiki/Bernoulli%27s_principle

Thinking

Now think about how airplanes get lift in the air? Does the air up the plane move faster than that under the plane? How does it work?