PHYSICS 1321 CHAPTER 12 –FLUID MECHANICS 1. Density (ρ)  Very important property of material , fluid or solid.  2 or more objects can have same density despite having different masses and volume if they are made of the same material.  Mass per unit volume 3  SI unit : kg/m  ρ=m/V 2. Pressure in fluid (p)  It is the force exerted per unit area.  The force exerted is perpendicular to any surface.  Scalar Quantity  SI unit : 1 Pa = 1 N/m 2  p=(dF)/(dA) 3. Pressure at depth in a fluid  Pressure at depth is greater than pressure p whic0 is at surface  p=p +0ρgh --------- (1)  In a column, the pressure at the top of each liquid column is p . At 0he bottom , the pressure is p. The difference in p and p is ρ0h. 4. Pascal’s Law  Pressure applied to an enclosed fluid is transmitted to every potion of the fluid undiminished and equally.  p=(F )1(A )1= (F )2(A )2 5. Absolute Pressure and Gauge Pressure  Total pressure is p atm .  The excess pressure above atmospheric pressure is called gauge pressure .  If the pressure applied is less than atmospheric , the gauge pressure is negative. 6. Archimedes’ Principle  When a body is submerged in water , it weighs less as compared to when in air.