Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds
 

Bernoulli experiments with sheets of paper

Class practical

This quick activity could be used as a starting point for discussion of atmospheric pressure.

Apparatus and materials

For each pupil

Thin paper (up to 80 gsm), 2 sheet

Health & Safety and Technical notes


Read our standard health & safety guidance

 

Procedure


student blowing between sheets of paper vertically

a Hold two pieces of thin paper vertically a short distance apart and blow down into the space between them. 

student blowing into paper horizontally

b Hold one end of a small sheet of paper in both hands. Keep the held edge horizontal while the other end sags under its own weight. Blow steadily over the top of this horizontal edge. 


Teaching notes


1 It seems amazing that the two sheets of paper move closer together. In both cases, pressure is reduced where air is moving quickly. This is called the Bernoulli principle. 

2 Some squeaker toys make their noise with blades like those two sheets of paper. Vocal chords act in the same way. 
 
3 The diagrams below illustrate how a plane takes off. The moving plane starts a vortex of air circulating round the wing. The vortex combines with the general flow of air past the plane so that the combined flow pattern leads to faster air above the wing and hence less pressure above the wing. The higher pressure below the wing then creates lift. 

Vortex of air

The image below shows a cross-section through the wing. 

A crossection of the vortex

This experiment was safety-checked in March 2005

 

Related experiments


Bernoulli effect demonstration