This topic covers the basic concepts of heat energy, its sources, transfer mechanisms, and units of measurement. Students will learn about the principles of thermal equilibrium and the difference between heat and temperature.
Introduction to Heat Energy – Study Notes
| Concept | Explanation | Typical Symbol |
|---|---|---|
| Temperature | Measure of the average kinetic energy of particles in a substance. | (T) |
| Internal Energy (U) | Total microscopic kinetic + potential energy of all particles in a system. | (U) |
| Heat (Q) | Energy transferred because of a temperature gradient. | (Q) |
| Work (W) | Energy transferred by forces acting through a distance (e.g., compression, expansion). | (W) |
| First Law of Thermodynamics | Energy cannot be created or destroyed; (\Delta U = Q - W). | — |
| Mode | Mechanism | Typical Examples |
|---|---|---|
| Conduction | Direct molecular collisions transfer kinetic energy through a material. | Metal rod heated at one end. |
| Convection | Bulk movement of fluid (liquid or gas) carries heat. | Boiling water, atmospheric circulation. |
| Radiation | Emission of electromagnetic waves (infrared) from a body’s surface. | Sunlight, heat from a fireplace. |
Specific Heat Capacity (c)
Latent Heat
Heat Flow Rate
| Quantity | SI Unit | Common Non‑SI Units |
|---|---|---|
| Energy / Heat | Joule (J) | calorie (cal), British Thermal Unit (BTU) |
| Power (heat rate) | Watt (W = J s⁻¹) | kilowatt (kW), horsepower (hp) |
| Specific Heat | J kg⁻¹ K⁻¹ | cal g⁻¹ °C⁻¹ |
| Latent Heat | J kg⁻¹ | cal g⁻¹ |
Conversion: 1 cal ≈ 4.184 J; 1 BTU ≈ 1055 J.
| Field | Application | Heat‑Energy Principle |
|---|---|---|
| **Domestic heating |