Heat is the transfer of thermal energy from a hotter object to a cooler one due to a temperature difference. It flows naturally until thermal equilibrium is reached.
Temperature measures the average kinetic energy of particles. Heat is energy in transit. Two objects at the same temperature can hold different amounts of heat.
Heat is measured in Joules (J). A large lake at 20°C holds far more heat than a tiny cup of boiling water at 100°C — because of greater mass.
Metals conduct heat rapidly because free electrons carry energy quickly. Wood and plastic are insulators — heat moves very slowly through them.
Conduction
Through direct contact. Particles vibrate and pass energy to neighbours. Best in solids especially metals.
Convection
Through fluid movement. Hot fluid rises, cool sinks, creating currents. Occurs in liquids and gases.
Radiation
Via electromagnetic waves with no medium needed. The Sun heats Earth through 150 million km of vacuum.
Click a type to see diagram and details →
Temperature is the measure of the average kinetic energy of the particles of a substance. It tells us how hot or cold a body is.
Temperature determines the direction of heat flow. Heat always moves from higher to lower temperature — never the reverse spontaneously.
Higher temperature → faster particles → more heat transferred per second
A pool at 30°C has more total heat than a cup at 80°C — greater mass holds more energy.
Equal temperature = no net heat flow (thermal equilibrium)
| Convert | Formula |
|---|---|
| °C → °F | F = (9÷5 × C) + 32 |
| °F → °C | C = 5÷9 × (F − 32) |
| °C → K | K = C + 273 |
| K → °C | C = K − 273 |
Worked Examples
Step-by-step examples with formulas
3 Examples →Interactive Practice
Choose correct steps to solve yourself
5 Questions →📊 Orange (200 mL): Rises slower — needs more heat per °C.
📌 Conclusion: Q = mc∆T — more mass needs more heat for the same temperature rise!