Lecture 2 - Hydrostatics

Question 1

What is absolute- , relative- , gage-, and vacuum pressure?

Answer 1

Absolute pressure: The actual pressure at at given position
**Relative pressure: **Local atmospheric pressure
Gage pressure: Difference between absolute pressure and relative pressure
Vacuum pressure: Pressure below atmospheric pressure

Question 2

How can you calculate gage- and vacuum pressure?

Answer 2

Pgage = Pabs - Patm
Pvac = Patm - Pabs

Question 3

What is the definition of Stewins law?

Answer 3

In a fluid at rest there are no shear forces and pressure is isotropic (equal in all directions; invariant under rotation). The pressure at any point in a static fluid acts with the same magnitude in all directions.

Question 4

How do you calculate pressure difference?

Answer 4

ΔP =ρgh