PRESSURE

-
Pressure Terminology 
P=ρgh
There are three different kinds of pressure reported in the literature, and it is important to know the terminology:
1.      Absolute pressure is measured relative to absolute zero on the pressure scale, which is a perfect vacuum. (Absolute pressure can never be negative.) Absolute pressure is indicated by P and is identical to the familiar thermodynamic pressure.

2.      Gage pressure (sometimes written as "gauge pressure") is measured relative to the local atmospheric pressure. Gage pressure is thus zero when the pressure is the same as atmospheric pressure. (It is possible to have negative gage pressure.) Gage pressure is indicated by Pg and is related to absolute pressure as follows: Pg = P - Pa, where pa is the local atmospheric pressure.

3.      Vacuum pressure is also measured relative to the local atmospheric pressure, but is used when the gage pressure is negative, i.e. when the absolute pressure falls below the local atmospheric pressure. (Positive vacuum pressure means that the gage pressure is negative.) Vacuum pressure is indicated by Pvacuum and is related to absolute pressure as follows: Pvacuum = Pa - P, where pa is the local atmospheric pressure.

Ptotal​=ρgh+Patm​


EXAMPLE
1.      Pressure acting in water at depth 1 m. The density of water at 4oC is 1000 kg/m3. The pressure acting in water at 1 m can be calculated as
Solution:
p = ρ g h 
   = (1000 kg/m3) (9.81 m/s2) (1 m) 
   = 9810 Pa


2.      Pressure acting in water at depth 3 ft. The density of water at 32oF is 1.940 slugs/ft3. The pressure acting in water at 3 ft can be calculated as
Solution:
p = ρ g h
   = (1.940 slugs/ft3) (32.17405 ft/s2) (3 ft) 
   = 187.3 lbf/ft2 (psf)
   = 1.3 lbf/in2 (psi)

ABOUT US

We are students of Bachelor Degree of Civil Engineering Technology (Environmental) with Honours from University Tun Hussein Onn Malaysia. Our teammates are:

1. MUHAMMAD AFIQ BIN ZABIDI (AN170093)

2. MUHAMMAD ARIF RIDZUAN BIN MD KHALIL (AN170061)

3. NUR IZZAH BINTI MOHAMAD KETAR @ MOKHTAR (AN170125)

4. NUR LAILA BINTI OSMAN (AN170083)

5. NUR IZZMIRZA BINTI MOHSIN (CN170013)

Popular posts from this blog

ARCHIMEDES' PRINCIPLE

-
Image
What is Archimedes' Principle? Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces and acts in the upward direction at the center of mass of the displaced fluid. Archimedes' principle is a law of physics fundamental to fluid mechanics. It was formulated by Archimedes of Syracuse.  Archimedes' principle does not consider the surface tension (capillarity) acting on the body.  Moreover, Archimedes' principle has been found to break down in complex fluids . Fb = ρgV = ρghA Fb = buoyant force of a liquid acting on an object (N) ρ = density of the liquid(kg/m3) g = gravitational acceleration(9.80 m/s2) V = volume of liquid displaced (m3 or liters, where 1 m3 = 1000 L) h = height of water displaced by a floating object(m) A = surface area of a floating object(m2) Buoyancy Formula Questions: 1.   A
Read more

BERNOULLI EQUATION

-
Image
BERNOULLI EQUATION An approximate relation between pressure, velocity and elevation and valid in regions of steady, incompressible flow where net frictional forces are negligible. In simple way to understand, to know the relationship between pressure and fluid velocity in the flow system. Despite its simplicity, it has been proven to be very powerful tool in fluids mechanics which fluid motion is governed by the combined effects of pressure and gravity forces.  There are 3 types main energy in the moving fluid which are: ·       Potential energy, energy which possessed by fluid based on potential head (the height at point in fluid flow measured from datum or reference line). P energy = Z (m) ·      Kinetic energy, energy possessed by the fluid particles based on it velocity. K energy = v 2 / 2g (m) ·      Pressure energy, energy possessed by fluid based on the pressure in the fluid. P = ρgh Therefore, h = P / ρg BERNOULLI THEOREM APP
Read more

CONCLUSION

-
Image
Pressure, Archimedes and Bernoulli and the continuity equations are the most fundamental equations in Fluid Mechanics. They will be used very frequently in the next chapter after this. In chapter Four which is Basic Equations in Fluid Mechanic, either the Bernoulli equation or the continuity equation is used together with the mass and momentum equations to find out the torques and forces acting on fluid systems. So, it is very important for all of us to understand this equation. To wrap up this chapter, we can conclude that, Archimedes Formula Volume Flow Rate Equation of Continuity   Bernoullis’s Equation REFERENCES: 1.  http://www.softschools.com/formulas/physics/buoyancy_formula/28/ 2.  Acott, Chris (1999). "The diving "Law-ers": A brief resume of their lives". South Pacific Underwater Medicine Society journal. 29 (1). ISSN 0813-1988. OCLC 16986801. Retrieved 2009-06-13. 3.  "Floater clustering in a standing wa
Read more