Physics

• E.m.f.


  Energy transferred from source (eg chemical energy in cell) per unit charge
• Progressive wave


  Transfers energy as a result of oscillations
• Yield point


  The stress beyond which a material becomes plastic
• Tera


  ^12
• Giga


  ^9
• Mega


  ^6
• Kilo


  ^3
• milli


  ^-3
• Micro


  ^-6
• Nano


  ^-9
• Pico


  ^-12
• Normal contact force


  Perpendicular reaction by the surface due to a force acting against it ( often weight)
• Terminal velocity


  Velocity at which an object's drag equals its accelerating force. There is no resultant force and no acceleration
• Moment


  Product of a force and the perpendicular distance of its line of action from the point
• Couple


  Occurs when two equal, antiparallel forces act to produce a rotation
• Torque


  Moment or turning effect of a couple
• Centre of mass


  The single point at which all of the mass of an object can be assumed to be situated
• Centre of gravity


  The point at which the entire weight of an object can be considered to act
• Work done


  Force multiplied by displacement in direction of force
• Deformation


  Change in size or shape of an object
• Stress


  Force per unit area
• Strain


  Extension per unit length
• Ultimate tensile strength


  The maximum stress a material can withstand before it fails or breaks
• Elastic potential energy


  The energy stored in a stretched or compressed object
• Newton's First Law


  An object will remain at rest or in uniform motion unless acted upon by an external force
• Newton's Second Law (simple)

  F=ma or in words, the acceleration of a body is directly proportional to the resultant force causing it and inversely proportion to the mass of the body.
• Newton's Third Law


  Every action has an equal and opposite reaction
• Perfectly elastic collision


  Momentum and Kinetic Energy conserved
• Inelastic collision


  Momentum but not Kinetic Energy conserved
• Kirchoff's First Law


  Charge is conserved in the junctions of a circuit
• Kirchoff's Second Law


  Energy is conserved in a circuit (E.m.f.=sum of p.ds)
• Drift velocity


  The average speed at which electrons move along a wire
• Potential difference


  Energy transferred per Coulomb of charge transferred between two points (difference in electrical potential energy)
• Electromotive force


  Theoretical maximum potential difference available from a cell
• Resistivity


  Level of resistance to a current (measured in ohm metres)
• Power


  Rate of transfer of energy
• Lost volts


  Lost within internal supply so not used in circuit
• Longitudinal wave


  Oscillations are parallel to the direction of energy transfer (sound)
• Transverse wave


  Oscillations are perpendicular to the direction of energy transfer (light)
• Displacement


  The distance any part of the wave has moved from equilibrium