Temperature is a measure of the average kinetic energy of the particles in a substance. When you feel a hot cup of tea, you're sensing the higher kinetic energy of the tea molecules.
The kinetic energy of a particle is given by \$K = \frac{1}{2}mv^2\$. In a solid, liquid or gas, the particles vibrate, move or collide, and the average kinetic energy determines the temperature.
Specific heat capacity (\$c\$) is the amount of heat required to raise the temperature of 1 kg of a substance by 1 °C (or 1 K). It tells us how much energy is needed to increase the average kinetic energy of all particles.
Key formula: \$q = m\,c\,\Delta T\$ where \$q\$ is heat added, \$m\$ mass, \$c\$ specific heat, and \$\Delta T\$ temperature change.
Imagine a pot of water on a stove. The stove supplies heat energy. Each joule of heat increases the kinetic energy of the water molecules, making them move faster. The more water you have (larger \$m\$), the more heat you need to raise its temperature by the same amount.
| Material | Specific Heat Capacity (J kg⁻¹ K⁻¹) |
|---|---|
| Water | 4184 |
| Aluminium | 900 |
| Iron | 450 |
| Copper | 385 |
Tip: When you see a question about heat transfer, first decide whether you need to use \$q = m\,c\,\Delta T\$ or \$q = m\,\Delta H\$ (for phase changes). Remember that specific heat capacity is a property of the material, not of the sample.
Also, check the units: \$c\$ is in J kg⁻¹ K⁻¹, \$m\$ in kg, \$\Delta T\$ in K. The product gives heat in joules.