Heat

The three methods of heat transfer — conduction, convection, and radiation — with everyday examples.

Specific heat capacity tells us how much energy is needed to raise the temperature of 1 kg of a substance by 1°C. Different materials need different amounts of energy to heat up. The formula Q = mcΔT connects energy, mass, specific heat capacity, and temperature change.

Matter exists as a solid, liquid, or gas. The particle model explains the properties of each state. Solids have fixed shape and volume; liquids flow but have fixed volume; gases fill their container. Changes between states involve energy being transferred.

Temperature is a measure of how hot or cold something is. Scientists use the Kelvin scale, which starts at absolute zero, while everyday life uses Celsius. Converting between them requires adding or subtracting 273.

Most materials expand when heated and contract when cooled. This is called thermal expansion, and it happens because particles vibrate more at higher temperatures.