Tuesday 8 October 2013

Science: Bernoulli's principle and a Magical Ping Pong Ball!

The concentration in this face! It doesn't show you how much My Honi loved it and ow many times she played with this science project.  It's fun, it's magic and it teaches about air pressure and thermal currents!  It was also a huge hit at the science group I run so...

Want to know more about it? Well...

It's like this the hot air that blows out of the hair dryer makes for a tunnel of low pressure.  The colder air around this tunnel of warm air is higher in pressure so pushes against the low pressure and, because the ping pong ball is so light, pushes the ping pong ball keeping in the tunnel of low pressure.

Amazingly it still works when you tilt the hair dryer for the same reason...

It's the same as with the Kissing balloons experiment but instead of someone blowing the air molecules away, the hair dryer is what blows away most of the air molecules and makes this tunnel of low air pressure.
High pressure always pushes on low pressure and therefore pushes at the ping pong ball which is light and is in the area of low pressure which is what keeps it from falling even when tilted!
Cool hey! This is a great practical experiment to prove Bernoulli's principle:
In fluid dynamics, Bernoulli's principle states that for an inviscid (a fluid with no viscosity) flow, an increase in the speed of the fluid occurs at the same time with a decrease in pressure or a decrease in the fluid's potential energy.  It is also found that this theory is applicable with air and aerofoil and in thermodynamics.
This is what has happened here, we increased the speed of flow of air (the hairdryer) and this decreases the energy making the energy around it higher.

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