Physics - FLUID MECHANICS

• Solids - fixed shape and size

  Liquid - no fixed shape but fixed size

  Gas - no fixed shape and size
• Plasma - ionized gas

  Liquid crystal - intermediate phase between solids and liquids

  Fluid Statics - study of fluids in equilibrium (at rest)

  Fluid Dynamics - study of fluids in motion (fluid flow)
• Density

  > ratio of an object’s mass to its volume

  > measure of “compactness” of an object

  > SI Unit is kg/m^3

  > P = m/v
• Specific gravity

  
  

  > ratio of the density of an object to the density of water at 4.0C which is 1000kg/m^3

  > factor to determine if it will float on water
• Pressure - force per unit area, SI Unit is Pascal (Pa)
• Atmospheric Pressure - > pressure exerted by the atmosphere on any object in it
• Pressure, Depth and Pascal's Law

  -> a fluid can exert pressure in any direction

  -> force due to liquid pressure always acts perpendicular to any solid surface in contact with it

  -> varies with depth (h)
• Pressure is the same at any two points at the same level in a fluid. The shape of the container does not matter.
• Pascal's Law

  > principle applied when applying external pressure

  > attributed to Blaise Pascal
• Pascal's Law - "Pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and the walls of the containing vessel."
• Gauge Pressure

  -> pressure above and beyond the atmospheric pressure

  -> pressure given by a pressure gauge (device for measuring pressure)
• Absolute Pressure - total pressure
• Pressure Gauges - device used to measure pressure
• Manamoter - > pressure gauge for measuring gauge pressure using a U - tube
• Bourdon Gauge - pressure gauge for measuring gauge pressure using a spiral metal tube
• Barometer - pressure gauge for measuring atmospheric pressure
• Buoyancy - ability to float
• Archimede's Principle - "The buoyant force on an object immersed in a fluid is equal to the weight of the fluid displaced by that object."
• Surface Tension - restoring force exerted by a liquid when its deformed
• Fluid flow - fluids in motion (hydrodynamics -– water)
• Ideal Fluid - incompressible and has no internal friction ( viscosity)
• Viscosity - fluid’s internal friction when an object flows through it
• Flow line - path of an individual particle moving in a fluid
• Steady Flow - overall pattern does not change with time
• Flow Tube - flow line passing through an imaginary element of area
• Laminar Flow - smooth flow (patterned flow) where flow lines do not cross
• Turbulent Flow - flow with no patterns and flow lines may cross each other
• Continuity Equation

  -> applicable when the diameter of the flow tube changes

  
• Bernoulli's Principle

  > principle for fluid motion

  > attributed to Daniel Bernoulli

  FLUID MOTION > high pressure to low pressure
• Bernoulli's Principle

  "Where the velocity of the fluid is high, the pressure is low and where the velocity of the fluid is low, the pressure is high."
• BERNOULLI’s EQUATION

  > relates pressure, flow speed and height of a flow tube