Definitions A2 Physics
Circular Motion
Radian: Angle (subtended) where arc (length) is equal to radius (angle subtended) at the centre of
a circle.
Angular Velocity: Rate of change of angle / angular displacement swept out by radius.
Gravitational Field
Newtons Law of Gravitation: Two-point masses attract each other with a force that is proportional
to product of their masses and inversely proportional to the square of their separation.
Gravitational Field Strength: Gravitational force experienced by an object per unit mass.
Gravitational Potential: Work done per unit mass bringing (small test) mass from infinity (to the
point).
Geostationary Orbit: Equatorial orbit / above equator satellite moves from west to east / same
direction as Earth spins period is 24 hours / same period as spinning of Earth.
Geostationary Satellite: Satellite is in equatorial orbit travelling from west to east period of 24
hours / 1 day.
Gravitational Field: Region of space area / volume where a mass experiences a force.
Potential Energy: Ability to do work as a result of the position/shape, etc. of an object
Oscillations
Angular Frequency: (angular frequency =) 2π × frequency or 2π/ period
Oscillations: To-and-fro / backward and forward motion (between two limits).
Simple Harmonic Motion: Type of vibratory motion in which acceleration/force proportional to
displacement (from fixed point) and acceleration/force and displacement in opposite directions.
Free Oscillations: (body oscillates) Without any loss of energy/no resistive forces/no external
forces applied.
Forced Oscillations: Continuous energy input (required)/body is made to vibrate by an
(external) periodic force/driving oscillator.
Forced Frequency: Frequency at which object is made to vibrate/oscillate.
Natural Frequency: Frequency at which object vibrates when free to do so.
Resonance: Maximum amplitude of vibration of oscillating body when forced frequency equals
natural frequency (of vibration).
Damping: Reduction in amplitude / energy of oscillations due to force (always) opposing motion /
resistive forces.
, Communication Systems
Amplitude Modulation: Amplitude of carrier wave varies in synchrony with displacement of
information signal.
Noise: random (unwanted) signal / power that masks / added to / interferes with / distorts
transmitted signal.
Regeneration: Noise/distortion is removed (from the signal) the (original) signal is
reformed/reproduced/recovered/restored
Or
Signal detected above/below a threshold creates new signal of 1s and 0s.
Frequency Modulation: Frequency of carrier wave varies in synchrony with the displacement of the
signal/information wave.
Attenuation: (gradual) Loss of power/intensity/amplitude (not “signal”).
Modulated Carrier Wave: High frequency wave the amplitude or the frequency is varied the
variation represents the information signal /in synchrony with (the displacement of) the
information signal.
Crosslinking: Signal in one wire (pair) is picked up by a neighboring wire (pair).
Parallel to serial Convertor: Receives bits all at one time transmits the bits one after another.
Digital Signal: (series of) ‘highs’ and ‘lows’ / ‘on’ and ‘off’ / 1’s and 0’s / two values with no
intermediate values / the values are discrete.
Analogue Signal: Signal that is continuously variable. Signal has same variation (with time) as the
data.
Analogue to Digital Convertor: Analogue signal is sampled at (regular time) intervals sampled
signal is converted into a binary number.
Cross Talk: Picking up of signal in one cable from a second (nearby) cable.
Thermal Physics
Specific Latent Heat: (thermal) energy required to change the state of a substance per unit mass
without any change of temperature.
Internal Energy: The sum of random distribution of kinetic and potential energies of the atoms or
molecules in a system.
Thermal Equilibrium: Same temperature no (net) transfer of thermal energy (between the bodies).
Specific Heat Capacity: The (thermal) energy per unit mass to raise the temperature of a substance
by one degree.
Circular Motion
Radian: Angle (subtended) where arc (length) is equal to radius (angle subtended) at the centre of
a circle.
Angular Velocity: Rate of change of angle / angular displacement swept out by radius.
Gravitational Field
Newtons Law of Gravitation: Two-point masses attract each other with a force that is proportional
to product of their masses and inversely proportional to the square of their separation.
Gravitational Field Strength: Gravitational force experienced by an object per unit mass.
Gravitational Potential: Work done per unit mass bringing (small test) mass from infinity (to the
point).
Geostationary Orbit: Equatorial orbit / above equator satellite moves from west to east / same
direction as Earth spins period is 24 hours / same period as spinning of Earth.
Geostationary Satellite: Satellite is in equatorial orbit travelling from west to east period of 24
hours / 1 day.
Gravitational Field: Region of space area / volume where a mass experiences a force.
Potential Energy: Ability to do work as a result of the position/shape, etc. of an object
Oscillations
Angular Frequency: (angular frequency =) 2π × frequency or 2π/ period
Oscillations: To-and-fro / backward and forward motion (between two limits).
Simple Harmonic Motion: Type of vibratory motion in which acceleration/force proportional to
displacement (from fixed point) and acceleration/force and displacement in opposite directions.
Free Oscillations: (body oscillates) Without any loss of energy/no resistive forces/no external
forces applied.
Forced Oscillations: Continuous energy input (required)/body is made to vibrate by an
(external) periodic force/driving oscillator.
Forced Frequency: Frequency at which object is made to vibrate/oscillate.
Natural Frequency: Frequency at which object vibrates when free to do so.
Resonance: Maximum amplitude of vibration of oscillating body when forced frequency equals
natural frequency (of vibration).
Damping: Reduction in amplitude / energy of oscillations due to force (always) opposing motion /
resistive forces.
, Communication Systems
Amplitude Modulation: Amplitude of carrier wave varies in synchrony with displacement of
information signal.
Noise: random (unwanted) signal / power that masks / added to / interferes with / distorts
transmitted signal.
Regeneration: Noise/distortion is removed (from the signal) the (original) signal is
reformed/reproduced/recovered/restored
Or
Signal detected above/below a threshold creates new signal of 1s and 0s.
Frequency Modulation: Frequency of carrier wave varies in synchrony with the displacement of the
signal/information wave.
Attenuation: (gradual) Loss of power/intensity/amplitude (not “signal”).
Modulated Carrier Wave: High frequency wave the amplitude or the frequency is varied the
variation represents the information signal /in synchrony with (the displacement of) the
information signal.
Crosslinking: Signal in one wire (pair) is picked up by a neighboring wire (pair).
Parallel to serial Convertor: Receives bits all at one time transmits the bits one after another.
Digital Signal: (series of) ‘highs’ and ‘lows’ / ‘on’ and ‘off’ / 1’s and 0’s / two values with no
intermediate values / the values are discrete.
Analogue Signal: Signal that is continuously variable. Signal has same variation (with time) as the
data.
Analogue to Digital Convertor: Analogue signal is sampled at (regular time) intervals sampled
signal is converted into a binary number.
Cross Talk: Picking up of signal in one cable from a second (nearby) cable.
Thermal Physics
Specific Latent Heat: (thermal) energy required to change the state of a substance per unit mass
without any change of temperature.
Internal Energy: The sum of random distribution of kinetic and potential energies of the atoms or
molecules in a system.
Thermal Equilibrium: Same temperature no (net) transfer of thermal energy (between the bodies).
Specific Heat Capacity: The (thermal) energy per unit mass to raise the temperature of a substance
by one degree.
