Water manometer to measure change in pressure

AI Thread Summary
The discussion revolves around an experiment using a water manometer to measure the change in pressure of a gas after heating. The initial atmospheric pressure is given as 1.4 x 10^5 Pa, and the user attempts to calculate the gauge pressure based on the height difference in water columns. The calculation of pressure using the formula P = pgd leads to confusion, as the user mistakenly converts the result to kPa instead of keeping it in Pa. The correct calculation indicates that the change in pressure is 392.1 Pa, clarifying the misunderstanding regarding unit conversion. Accurate understanding of pressure measurement is crucial for the experiment's success.
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Homework Statement



An experiment to determine the specific heat of a gas makes use of a water manometer attached to a flask (the figure below ). Initially the two columns of water are even. Atmospheric pressure is 1.4 x 10^5 Pa. After heating the gas, the water levels change to those shown. Find the change in pressure of the gas in Pa.

https://chip.physics.purdue.edu/protected/GiambattistaMimg/chapter-09/fig-035.gif

Homework Equations



P = pgd (gauge pressure)
Pgauge = Pabs - Patm

The Attempt at a Solution



well, i took (1000 kg/m3)x(9.81m/s2)x(.04m) and got 392.4 kPa...that's 392400 Pa, right?
but it's not correct...where did i go wrong? i know that it is displaced .02m up and .02m down for a total of .04m, and the density of water is 1000kg/m3 (for this problem)

any help would be appreciated!
 
Physics news on Phys.org
1000x9.81x.04 = 392.1Pa., not kPa
 

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