So when we have a U-shaped barometer we say that the way we can measure atmospheric pressure is by measuring the difference in the height of the liquid, and the pressure exerted by the same. I am a little confused as to why this is the case. Why should the pressure at two points in a liquid which are the same height be the same, when there is a column of liquid above the other.
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If there was a difference in pressure then the fluid would move so that the pressure became the same. Equal pressure really is just the same thing as equal forces (expressed per unit area).
Why should the pressure at two points in a liquid which are the same height be the same, when there is a column of liquid above the other.
The first part of that statement is usually said for fluids where the only force present is gravity. Of course in your barometer case, if there are unequal pressures being applied to each side you will get a difference in water height (but still the same pressure at a given height in the fluid).
answered Oct 24, 2019 at 2:04