Absolute Pressure vs. Gauge Pressure The absolute pressure inside a closed chamb
ID: 1483359 • Letter: A
Question
Absolute Pressure vs. Gauge Pressure
The absolute pressure inside a closed chamber, like a tire, is the sum of
atmospheric pressure pushing down on the outside of the chamber, and
the additional pressure of the fluid that is inside the chamber.
Pressure gauges do NOT measure absolute pressure.
Gauge pressure is the difference between the
pressure inside and outside a closed chamber.
Pgas =
Pgas = Pa
The apparatus shown in the figure is used topressurize the gas in the closed chamber.
The weighted piston pushing down on the fluid
in the righthand tube raises the level of fluid
in the tube on the left, compressing the
gas and increases its pressure.
The gauge pressure of the gas is measured
after the system reaches equilibrium.
The cross-sectional area of the piston is A = 54 m2,
and the fluid density is = 1410 kg/m3.
The variation in gas pressure with depth is
negligible compared to the pressure of the gas.
Explanation / Answer
Here
a) for the pressure of the gas
Pgas - PA = p * g *h
Pgas = W/A + p * g * h
the gas pressure is W/A + p * g * h
b)
Pgas = 24.8/(54) + 1410 * 9.8 * 0.85
Pgas = 11745.8 Pa
the pressure in the gas is 11745.8 Pa