Solid and fluids

• Properties of solid

  Strong, stiff, tough, elastic, hard, ductile, malleable, weak, flexible, brittle, plastic, soft, hard brittle
• Strong 


  High breaking stress
• Stiff


  gradient of force-extension graph; high young modulus
• Tough


  High energy density up to fracture; metal that has a large plastic region
• Elastis


  regains original dimensions when the deforming force is removed
• Hard


  difficult to indent the surface
• Ductile 


  can be readily drawn into wires
• Malleable 


  can be hammered into thin sheets
• Weak


  low breaking stress
• flexible 


  low young modulus
• Brittle 


  little or no plastic deformation before fracture
• Plastic


  extends extensively and irreversibly for a small increase in stress beyond the yield point
• soft


  surface easily intended/scratched
• Hooke's law 


  the proportionality of stress and strain in elastic deformations
• Stress


  measure of forces applied to deform a body
• Measure of how much deformation result from stress

  strain
• Elastic modulus


  property of material of which body is made
• SI unit of stress

  N/m^2 or pascal (Pa)
• Liquid


  'Large' molecular spacing relative to a solid
• Weak


  intermolecular cohesive forces
• Density 


   mass of a unit volume of a material substance. 
• Fluid pressure


  is the average effect of many impacts resulting from molecule to wall collisions
• Forces exerted by liquid on the walls of its container are always perpendicular
• Liquid pressure is directly proportional to the depth of the fluid and to its density
• At any specific depth, the fluid pressure is the same in all directions
• Liquid pressure is independent of its container's shape/area. Liquid find its own level
• Atmospheric pressure


  is caused by a mixture of gases, results from gravity holding air molecules downward in/on the Earth's atmosphere
• Standard pressure or standard atmosphere pressure

  is average normal pressure at sea level
• As you go ABOVE sea level, pressure is less
• As you go BELOW the sea level, pressure is greater
• Standard pressure


  is defined as atmosphere whose temperature is at 15 degree at latitude 45 degree
• 1 atm= 1013.25 hPa
• The direction of pressure is always perpendicular to the area being considered but at any particular point in the fluid is equal in all directions.\
• Mercurial Barometer


  – standard instrument for determining atmospheric pressure
• Aneroid Barometer


  – mechanical device w/c registers pressure based on spring deformation
• Barograph


  – A recording aneroid barometer
• Laminar Flow


  – flow in which adjacent layers of fluid slide smoothly past each other and the flow is steady
• Streamline


  path traced out by fluid’s particle in a laminar flow
• Turbulent Flow


  flow is irregular, chaotic and its pattern changes continuously
• Eddies or Eddy Currents


  erratic, small, whirlpool-like circles in a turbulent flow (e.g. vortices)