# Why Would the Pressure at Points 1 and 2 be the Same?

#### colcol500

Homework Statement
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Homework Equations
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Why would the pressure at points 1 and 2 be the same? I understand they are at the same elevation and due to Pascal's law should have the same pressure, but isn't water denser than air? So in turn, wouldn't it exert more pressure than air? So then how come despite all the water pushing down on point 2, it is still the same pressure as point 1, which only has air pushing down on it???

Thank you

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#### tnich

Homework Helper
It might help you to think about the height of the column of air pushing down on the surface of the water in the tank. Also, think about what would happen if the pressures were not equal.

#### Chestermiller

Mentor
The system is supposed to be in static equilibrium. So, if you go downward beneath point 1 until you are lower than the tube, the pressure increases. Then if you go horizontally across under the edge of the tube, the pressure doesn't change. The, if you go back up within the tube to the same elevation as point 1, the pressure decreases again until you reach point 2. The net effect of this excursion is no change in pressure between points 1 and 2.

"Why Would the Pressure at Points 1 and 2 be the Same?"

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