Water and pressure reduction

[Gabriele]

this way....

[Gabriele]

I tried computate an immaginary sistem formed by weights and boxes allowing the weight is on the box full of air,after a compression,to move on the first...than let the compression i gave go,and to return the weight to the ground...i got a surplus. But probably is a mistake,cause i'm not really able to do that math,really i don't know how to do that...

Green and white go on red after compression...the red compress more,i let pressure decreese,and i re-put the green white on the ground

[MarkE]

On the left the water contributes pressure based on the water height.

Assigning X left to right, Y into page, and Z as height, and taking the 0,0,0 datum at the lower left hand corner:

Weight_water = 9.8m/s²*1000kg/m³*water_volume

Pressure_bottom_left = air_pressure + weight_water/(x_wall * y)

Force_left_to_right = y * ( 0.5*pressure_bottom_left*z_water + air_pressure * z_wall )

=

Force_right_to_left = y * ( air_pressure * z_wall ) + Kspring * (box_width + x_wall - spring_uncompressed_length)   (spring K is negative value)

y * ( 0.5*(air_pressure + weight_water/(x_wall * y))*z_water ) = Kspring * (box_width + x_wall - spring_uncompressed_length) 

Solve for x_wall.

[Gabriele]

It is clear the wall moves. What for me isn't clear is,i repeat,if when i remove the compression when the level of water is rised,how much energy the water returns... 100% of elastic energy due to liquid compression or less? Thx

[Low-Q]

this way....

This shuld be "easy" to confirm if you had some mercury. And we can eleminate pressure as it is equal in both chambers anyways.


In the first experiment you use water - completely filled up. No pressure. Measure force acting on the wall.
In the next experiment, replace water with the same weight in mercury. No pressure. Measure force acting on the wall


Mercury is known to be denser than water. Well, the level of mercury would require only 7.4% of water level.
So imagine that the mercury is seriously compressed water. Water so compressed it has shrinked by 93.6% - that must require a very expensive pump, made by some very exotic materials!


Anyway. Then you can calculate the force that the mercury and water respectively is pushing on the wall. Do you find any difference?


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