Materials

• Upthrust = weight of fluid displaced
• F = 6 pi n r v

  F = viscous drag

  n = viscosity

  r = radius

  v = terminal velocity
• Conditions for Stoke’s law

  • object is small and spherical
  • low speed
  • laminar flow
• Laminar flow - when the particle in a fluid moves by following smooth paths with no mixing between layers.
• In a gas, as temperature decreases, viscosity increases
• Young’s modulus - describes the stiffness of a material
• Limit of proportionality - the point after which Hooke’s law is no longer obeyed
• Elastic limit - if the force is increased further, the material will deform plastically.
• Yield point - the point where the material begins to stretch without an increase in force
• Breaking stress - the maximum stress before a material will break apart
• The area under a stress - strain graph = the energy stored per unit volume