I saw this video on YT shorts where the guy demonstrates how it is impossible to suck water beyond 34 feet from the level it is stored at.
[This is the YT short](https://youtube.com/shorts/rWij9gJWcTg?si=5nTRvPUVFUKSaJmH)
On Google it says that the atmospheric pressure equals the pressure exerted by water column.
I don’t understand how that matters! Because in the end the guy attached a vacuum pump to pull the water up.
Also, if the water boils then it should also make steam.
Does PV=nRT apply there? I know it’s not ideal gas but for all practical purposes we use this equation.
In: Physics
Firstly, hydrostatic pressure. The higher the water column, the greater the pressure exerted by the weight of the water at the base of the column. But as a corollary, the greater the vacuum created at the top of the column.
https://en.wikipedia.org/wiki/Hydrostatics
It’s a bit like gravity pulling on a piston to create a vacuum in a chamber.
>On Google it says that the atmospheric pressure equals the pressure exerted by water column.
That’s not true. If the system is airtight, there’s no atmospheric pressure involved. When the system is an open reservoir, atmospheric pressure is added to absolute hydrostatic pressure to obtain absolute pressure. This is not the case with a depression tube used for pumping.
When the water column exceeds a certain size, the pressure becomes so low at the upper surface that the water evaporates at room temperature. This is what happens when cavitation occurs on a propeller.
https://en.wikipedia.org/wiki/Phase_diagram
This is why pumps are always installed at the lowest point of hydraulic systems. The aim is to avoid putting circuits under negative relative pressure, as this is inefficient and increases the risk of cavitation. We don’t like syphons and anything that can put circuits under vacuum in general, as most vessels are not designed to it and would end up like a crushed Coke can.
TL/DR:The guy in the YouTube video is making up nonsense.
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