- #1
Est120
- 51
- 3
Why does the pressure we take into account is the gage pressure and not the absolute pressure?
Reading Fundamentals of Momentum Heat and Mass transfer by Welty in chapter 2 it says "the magnitude of the force on the element dA is PgdA ,where Pg is the gage pressure"
my question is why the gage pressure ? it is supposed that the total pressure acting on that element of area dA is the absolute pressure (Patm+Pgage) why we don't take into account Patm?
Reading Fundamentals of Momentum Heat and Mass transfer by Welty in chapter 2 it says "the magnitude of the force on the element dA is PgdA ,where Pg is the gage pressure"
my question is why the gage pressure ? it is supposed that the total pressure acting on that element of area dA is the absolute pressure (Patm+Pgage) why we don't take into account Patm?