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azrida

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## Homework Statement

In the figure below, an open tube of length L = 1.8 m and cross-sectional area A = 4.6 cm2 is fixed to the top of a cylindrical barrel of diameter D = 1.2 m and height H = 1.8 m. The barrel and tube are filled with water (to the top of the tube). Calculate the ratio of the hydrostatic force on the bottom of the barrel to the gravitational force on the water contained in the barrel.

## Homework Equations

P=phg

F=mg=pvg

F=pa

F1/A1 = F2/A2

## The Attempt at a Solution

Okay, this problem has been giving me a major headache.

I tried to solve this by finding the gravitational force in barrel, which I assumed as:

mg = pvg = (1000kg/m^3)(0.6m^2*pi*1.8m)(9.8m/s^2) = 19940.256 N

Then I "attempted" to set up an equation to find the hydrostatic force on the bottom of the barrel, where I got stuck:

F1/A1=F2/A2

-> Atmospheric pressure/area of the tube = Hydraulic pressure/are of the bottom of the barrel

->??

I already know that the answer is 2, but I need to learn HOW and WHY it is so.

HELP, PLEASE! :-( !

pics at http://www.webassign.net/hrw/hrw7_14-31.gif

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