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Bernoulli's Principle


Arpa Ghazarian

Principles Illustrated

Bernoulli's Principle, air pressure, gravity, force, moving fluid, flow rate


Pressure is a force affecting certain properties of matter (Pascal’s Law, Bernoulli’s Principle, buoyancy). (8.PS.B15)

• Newton’s laws of motion that govern moving objects. (8.PS.B16)

Questioning Script

Prior knowledge & experience:

How do airplanes fly?

Root question:

1. What happens to the roll of paper when you blow air on the top surface of the paper?

2. What happens to the joined balloons when you blow air in between them? What happens to the balloons when you blow the sides of the balloons?

Target response:

When you create an area of faster air flow, the pressure is less in that area. 

1. When you blow air on top of the paper, the paper will go up because the pressure is greater from the bottom of the paper (slower moving air), than the top (faster moving air).

2. When you blow air in between the balloons, the balloons stay together and don't separate because the pressure from the sides of the balloons is greater, thus, keeping them together. If you blow air on the sides (faster air flow on the sides), it results in the balloons separating because the pressure in between the balloons is greater than that of the sides.

Common Misconceptions:

1. Blowing air on the top surface of the paper will make the paper go down. 

2. Blowing air in between the balloons should separate the balloons.

Photographs and Movies

Here are 2 demonstrations of this principle I have recorded:

Bernoulli's Principle