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Scalar

A quantity with magnitude only

Vector

A quantity with magnitude and direction

Systematic error

An error that shifts all readings in the same direction

Random error

An unpredictable variation in readings

Precision

How close repeated measurements are to each other

Accuracy

How close a measurement is to the true value

Resolution

Smallest change a measuring instrument can detect

Uncertainty

The interval within which the true value lies

Displacement

Distance moved in a specific direction

Velocity

Rate of change of displacement

Acceleration

Rate of change of velocity

Force

Rate of change of momentum

Momentum

Product of mass and velocity

Impulse

Change in momentum

Work done

Energy transferred by a force (force × distance)

Kinetic energy

Energy due to motion (½mv²)

Potential energy

Energy stored due to position

Power

Rate of energy transfer

Efficiency

Useful output ÷ total input

Density

Mass per unit volume

Pressure

Force per unit area

Stress

Force per unit cross-sectional area

Strain

Extension ÷ original length

Young modulus

Stress ÷ strain

Elastic deformation

Returns to original shape when force removed

Plastic deformation

Permanent deformation after force removed

Limit of proportionality

Point where stress no longer proportional to strain

Wave

Transfer of energy without transfer of matter

Transverse wave

Oscillations perpendicular to direction of travel

Longitudinal wave

Oscillations parallel to direction of travel

Wavelength

Distance between identical points on a wave

Frequency

Number of waves passing a point per second

Amplitude

Maximum displacement from equilibrium

Phase difference

Difference in position within a cycle

Superposition

When waves overlap, displacements add

Stationary wave

Wave with nodes and antinodes, no energy transfer

Diffraction

Spreading of waves through gaps

Refraction

Change in direction due to change in speed

Interference

Result of superposition of waves

Current

Rate of flow of charge

Charge

Quantity of electricity (Q = It)

Potential difference (p.d.)

Work done per unit charge

Resistance

Opposition to current (V/I)

Ohm's law

Current proportional to voltage (constant temperature)

Resistivity

Property of material affecting resistance

Power (electrical)

Rate of energy transfer (IV)

Electromotive force (emf)

Energy supplied per unit charge

Internal resistance

Resistance inside a power supply

Nucleon number (A)

Total number of protons and neutrons

Proton number (Z)

Number of protons

Isotopes

Same proton number, different neutron number

Radioactive decay

Spontaneous emission of radiation

Activity

Number of decays per second

Half-life

Time for activity or nuclei to halve

Alpha particle

Helium nucleus (2 protons and 2 neutrons)

Beta particle

Fast electron or positron

Gamma radiation

High-energy electromagnetic wave

Temperature

Measure of average kinetic energy of particles

Internal energy

Total kinetic and potential energy of particles

Specific heat capacity

Energy needed to raise 1 kg by 1°C

Specific latent heat

Energy required to change state without temperature change

First law of thermodynamics

Energy cannot be created or destroyed, only transferred

Gravitational field strength

Force per unit mass

Electric field strength

Force per unit charge

Potential (gravitational/electric)

Work done per unit mass or charge

Inverse square law

A law where field strength is proportional to 1 divided by distance squared

Centripetal force

Force directed towards the centre of a circular path

Angular velocity

Rate of change of angle

Period

Time for one complete cycle

Oscillation

Repetitive motion about an equilibrium position

Simple harmonic motion (SHM)

Acceleration proportional to displacement and opposite in direction

Period (oscillations)

Time for one complete oscillation

Frequency (oscillations)

Number of oscillations per second

Damping

Reduction in amplitude over time