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Q & A: Water pressure in various shaped vessels

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Most recent answer: 11/19/2012
Q:
We have 2 vessels: 1-An erlenmeyer flask with bottom area(a) and height(h). 2-A cylinder with bottom area(a) and height(h) again. I wanna to know how is the relation between water pressure exerted to bottom of these vessels. I read somewhere that they are equal,but i can't believe this,i think the pressure of cylinder's bottom is more than erlenmeyer's bottom pressure and equal to weight of water of each vessel devide to area(a). What is the truth?
- morteza (age 24)
tehra,iran
A:
Hello Morteza,
I think I know what your confusion is; it's the difference between the hydrostatic pressure of a liquid at the bottom of a vessel and the pressure between the vessel and a supporting table.  What your phrase,  'I read some somewhere...',  refers to is the hydrostatic pressure.  It is true, the hydrostatic pressure depends only on the height of the top of the liquid irrespective of the shape.   On the other hand your intuition about the pressure exerted by the vessel on the table depends on the total weight divided by the supporting area is correct.  In this case it does depend on the shape of the vessel for a given supporting area.
You can look at   for an explanation of the hydrostatic case.

LeeH

(published on 11/19/2012)

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