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The siphon

Another interesting application of liquid pressure is the siphon.



In the water siphon the water will flow out of the end of the tube A. (Figure 1). If a hole is made in the tube at P air will get in and the links between the water molecules will be broken and the flow will stop.

A siphon is useful for emptying ponds, water tanks etc. where you need to make the water 'flow uphill' at the start!

You can compare this with the movement of a chain over a pulley (Figure 2).



 
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© Keith Gibbs 2020