PH01

PH01

1. Mechanics

   • SUVAT
     • v = u + at
     • s = ut + ½at^2
     • v^2 = u^2 + 2as
   • Graphs
     • Displacement/Time Graphs
       • Gradient = velocity.
     • Velocity/Time Graph
       • Gradient = acceleration.
       • Area = displacement.
   • Scalars & Vectors
     • Scalars
       • A quantity with only magnitude.
     • Vector
       • A quantity with direction and magnitude.
   • Newtons Laws
     • First Law
       • An object will remain at rest unless acted on by an unbalanced force.
       • An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
     • Second Law
       • Acceleration is produced when a force acts on a mass. F=ma.
       • The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).
     • Third Law
       • For every action there is an equal and opposite re-action.
   • Gravitational Field Strength
     • g = F/m
     • W = mg
   • Energy
     • Kinetic
       • Ek = ½ mv^2
     • GPE
       • ∆Egrav = mg∆h
     • Work Done
       • ∆W = F∆s
       • Power
         • P = W/t

2. Materials

   • Viscosity
     • Viscosity - resistance to flow.
     • As temperature increases, viscosity decreases.
     • Thixotropy
       • E.g. Margarine
       • Viscous under normal conditions but less viscous when shaken, agitated, or otherwise stressed.
     • Stoke's Law
       • F = 6πηrv
   • Young's Modulus
     • E = stress/strain
     • Stress
       • stress = F/A
     • Strain
       • strain = ∆L/L
   • Deformation
     • Elastic deformation - recoverable deformation, once load removed object returns to original state.
       • Eel = ½ Fx
     • Plastic deformation - unrecoverable deformation, once load is removed object there is permanent deformation.
   • Terminology
     • Brittle - crack and breaks without plastic deformation.
     • Tough - Does not readily crack, can withstand dynamic loads such as shock or impact.
     • Ductile - can be deformed plastically under tension; can be pulled into a long thin shape.
     • Malleable - can be deformed plastically under compression; can be hammered into a sheet.
     • Hard - not readily scratched or indented.
     • Stiff - requires a large force to produce a small deformation.
     • Smooth - low friction surface.
     • Durable - properties do not worsen with repeated loading and unloading.