Pressure in Fluid Systems 1.2.2

Buoyancy and Archimedes’ Principle Archimedes’ Principle – an object immersed in a fluid has an upward force exerted on it equal to the weight of the fluid displaced by object. Because Vobject = Vfluid displaced

Buoyancy rules using weight of object. Buoyancy rules using density.

Pascal’s Principle A change in pressure at any point in a confined fluid is transmitted undiminished throughout the fluid (Fig 1.22) Formal expression or

Example 1.10, p 38

Atmospheric Pressure At sea level: 101.3 kPa = 760 mm Hg = 14.7 psi = 1 atm Measure with a barometer (see Fig 1.24, p. 39).

Absolute and Gauge Pressure Absolute pressure is the formal expression of the total force per unit area. It includes the pressure from the atmosphere (air pressure), the pressure from any external forces applied to the fluid and the pressure resultant from the weight of the fluid itself.

Pressure is Prime Mover Fluids Systems Liquid or gas that moves though a system of pipes. Pressure differences in the system create a net force which causes fluids to move or perform a function.

Equilibrium in a Fluid System Figures 1.26 to 1.28, pp. 42-43.