Materials

Materials

1. Air flow

   • Laminar flow
     • The flow lines are random and crossover each other, the velocity constantly changes
   • Turbulent flow
     • Flow lines are parallel to each other and don't overlap, they have a constant velocity

2. Stokes law

   • Where a sphere moves through a liquid relevant to the sphere is laminar
   • It is as though the particles of the fluid that are next to the sphere of radius r moving with a velocity of v relative to a fluid with a viscosity η
   • Viscous drag (f) = 6πrηv
     • This only works at low speeds
   • When a ball falls though fluid
     • Weight stays constant
     • Upthrust stays constant when the sphere is totally imeresed
     • The viscosity will stay the same
     • Velocity will increase until t.v
     • Viscous drag is proportional to velocity so increases as the ball gets faster
     • Terminal velocity
       • w=u+f
     • Accelerating velocity
       • Fr = w - (u+f)

3. Stress + strain

   • Stress is how much force a unit area is put under
     • stress = force / cross-sectional area
   • Strain is how much the material extends per unit length
     • Strain = Extension / original length
   • Young modules = stress/strain