Cambridge IGCSE Physics 4th Edition - Heather 2-95-136

physic chap 1

Kinetic particle model of matter

A model that explains the states of matter based on the behavior and interaction of tiny particles.

Solid

A state of matter with a definite shape and volume; particles are closely packed in fixed positions.

Liquid

A state of matter with a definite volume but no fixed shape; particles are close together but can slide past each other.

Gas

A state of matter that has no definite shape or volume; particles are well separated and move freely.

Brownian motion

Random motion of microscopic particles suspended in a medium, caused by collisions with much lighter molecules.

Evaporation

The process where particles escape from the surface of a liquid to become gas.

Condensation

The process where gas particles lose energy and change back into a liquid.

Thermal expansion

The increase in volume of a substance due to an increase in temperature.

Specific heat capacity

The amount of heat required to raise the temperature of one kilogram of a substance by one degree Celsius.

Absolute zero

The theoretical temperature at which the motion of particles theoretically ceases, measured at -273°C or 0 K.

Melting point

The temperature at which a solid turns into a liquid.

Boiling point

The temperature at which a liquid turns into a gas.

Latent heat of fusion

The amount of heat required to change a unit mass of a solid at its melting point into a liquid without a change in temperature.

Latent heat of vaporisation

The amount of heat required to change a unit mass of a liquid at its boiling point into a gas without a change in temperature.

Conduction

The transfer of thermal energy through a material without the movement of the material as a whole.

Convection

The transfer of thermal energy in fluids (liquids and gases) by the movement of the fluid itself.

Radiation

The transfer of thermal energy through electromagnetic waves; does not require a medium.

Thermal insulators

Materials that poorly conduct thermal energy, used to reduce heat transfer.

Thermal conductors

Materials that efficiently transfer thermal energy.

Charles' Law

The volume of a fixed mass of gas is directly proportional to its absolute temperature when pressure is kept constant.

Boyle's Law

The pressure of a fixed mass of gas is inversely proportional to its volume at constant temperature.

Kelvin scale

A thermodynamic scale used to measure absolute temperatures, starting at absolute zero.

Pressure law

The pressure of a fixed mass of gas is directly proportional to its absolute temperature if the volume is kept constant.

Thermal energy

The total kinetic energy of particles in a substance, related to temperature.

Density changes

Changes in a fluid's density that drive convection currents.

Thermal equilibrium

The state in which two objects in contact with each other cease to exchange energy, as they reach the same temperature.

Good absorbers and emitters

Surfaces that are effective at taking in thermal radiation and also releasing it; typically dark and rough.

Bad absorbers and emitters

Surfaces that reflect most radiation; typically smooth and shiny.