What are P and Pa in Gage Pressure vs Pa and P?

[evotunedscc]

Currently I'm in Fluid Mechanics. In a homework problem I'm given the gage pressure inside of a piezometer. In my book there's an equation p(gage) = p - pa . What are the P and the Pa?

 

[ekrim]

Currently I'm in Fluid Mechanics. In a homework problem I'm given the gage pressure inside of a piezometer. In my book there's an equation p(gage) = p - pa . What are the P and the Pa?

Gage pressure is simply the pressure reading if you exclude atmospheric pressure

in your equation, the gage pressure equals the absolute pressure minus the atmospheric pressure.

atmospheric is usually given around 101 kPa (kilo pascals)

 

[evotunedscc]

Excellent, thanks!