You are supposed to add that pressure to the atmospheric pressure.
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Absolute pressure is simply the addition of the observed gage pressure plus the value of the local atmospheric pressure.
No. We need to know exactly what is meant by gage here. A piston tyre gauge measures pressures relative to atmospheric. A mercury barometer measures absolute pressure. A gauge that involves uncoiling of a coiled tube will measure absolute pressure (it will have to be calibrated). But a manometer which is open to the atmosphere on one arm will measure pressures relative to atmospheric pressure so the real pressure is the two added together.
These are not the same dimension. Pounds force is a unit of force. PSI means pounds per square inch, which is a unit of pressure (force per unit area). The word gage refers to the fact that a pressure gage measures the difference between the pressure on the inside of a container and the outside. Normal atmospheric pressure is about 14 psi, so if a container of compressed air (like the tires on your car) measures 10 psi with a gage, the absolute pressure inside the tire is 14 + 10 = 24 pounds per square inch. The total force acting on a square inch of the tire material is 24 pounds - 10 pounds from the inside, and 14 pounds from the outside. Note, I approximated the 14 psi atmospheric. The actual at sea level is "14.something", I just couldn't remember the exact amount
hydrostatic pressureP= hdgwhere;p= pressure (N/m2 or Pa)h=height (m)d= density (kg/m3)g= acceleration due to gravity(9.81 m/s2)e.g.example problem.a pressure gage register 40 psig in a region where the barrometer is 14.5 psia. fine the absolute pressure in psia., and kPa(KN/m2)give.Pg= 40 psiaPo= 14.5 + 40p=54.5b. P=54.5psia=54.5 lb.....6894.8 N/m2In2 1 psi=37576606 N/m2375.77 KNp= 375.77 KPa
The smaller the gage the thicker the material; therefore, for the same material, 14 gage is stronger.