Definintions Flashcards
Centre of Mass
Point through which all the weight of an object is considered to act
Moment
Force multiplied by the perpendicular distance from the line of action of the force to the pivot
Couple
A pair of equal and opposite forces acting on a body but not along the same line (coplanar)
Displacement
Distance in a given direction from a fixed point
Velocity
Rate of change of displacement
Acceleration
Rate of change of velocity
Power
Rate of energy transfer/rate of doing work
Force
Rate of change of momentum
Impulse
Force x time for which the force acts
OR
change in momentum
Amplitude
Maximum displacement from equilibrium position
Frequency
Number of complete waves passing a point per unit time/per second
Time Period
Time taken to complete one oscillation
Wavelength
Distance between two identical positions on two adjacent waves
Wave Speed
Product of a waves frequency and wavelength
Phase
A measure of how far through the wave’s cycle a given point on the wave
is
Phase Difference
Difference in phase between two points on a wave
(in angles or fractions of a cycle)
Coherence
Same frequency/wavelength
Constant phase relationship
Path difference
How far ahead a wave is compared to another wave
Centripetal Force
Resultant force stopping a body from leaving the circle
Restoring Force
Resultant force acting on an oscillating object towards equilibrium position.
Resistance
Potential difference across a component per amp of current flowing through it.
Potential Difference
Amount of energy transformed when one coulomb of charge is moved between two points
Work done per unit charge
Current
Rate of flow of positive charge
Superconductor
Material with 0 resistivity below critical temperature
Critical Temperature
Temperature below which material becomes superconducting
EMF
The amount of energy transferred from chemical energy to electrical energy per unit charge
Terminal Potential Difference
Voltage across the terminals of a cell
Ohmic Conductor
Any component that conducts electricity and obeys Ohm’s law
Potential Divider
A circuit that shares the potential difference between components by connecting multiple resistors in series
Resistivity
How resistive a material is to allowing current to flow through it.
Work function
Minimum energy required to liberate an electron form the surface of a metal.
Photon
Small discrete packet of energy (no mass)
Stopping potential
Minimum potential difference required for 0 current in a photocell circuit
Electron volt
Energy gained by an electron as it accelerates through a potential difference of 1 volt
Excitation
When an electron moves to a higher energy levelby absorbing energy from an incident photon or electron
Ionistation
When an electron gains enough energy to leave the atom
Threshold Frequency
Minimum frequency of a photon for a photoelectron to be emitted from a metal surface
Elastic Behaviour
when a sample that has been deformed by a force returns to its original shape and size when the force causing the deformation is removed.
Plastic Behaviour
when the deforming force is removed the material does not return to its original shape/size.
Elastic Limit
maximum amount that a material can be stretched by a force, and still return to its original length when the force is removed
Yield Point
point at which the material extends considerably with no (or a very small) increase in force. The extension is permanent.
Ductile
easily and permanently stretched
Brittle
fractures very soon after the elastic limit, with little or no plastic deformation. (e.g. concrete, glass)
Potential divider
Circuit containing a combination of resistors in seriesacross a voltage source so that potential difference has been split
Ionisation Energy
Minimum energy t remove an electron from an atom from the ground state
