Bernoulli's Law

Demonstration of the Spray gun

Now, we know that fast flowing air causes relative low pressure while slow flowing air causes relative high pressure. High pressures tend to push things into low pressures. Have a look at the picture of the chimney. On windy days suggest how the chimney works. Identify the area of fast flowing air and slow flowing air, areas of high and low pressure.
Describe how smoke is removed when there is no wind present.
Chimneys obey Bernoulli's law.
When you suck your favourite drink through a straw you create an area of low pressure inside your mouth. Where is the relative high pressure situated to push the liquid into your mouth? Every time we suck through a straw we create areas of low and high pressure

You can make a simple spray gun at home using two straws. Explain how this simple spray gun works. Identify the areas of low pressure and high pressure.
You can create a simple spray gun at home with two straws. Click to see a 400kb movie.