Chapter 14: Thermal Physics

Heat

A form of energy transfer that occurs due to a temperature difference, measured in joules (J).

Temperature

A measure of the average kinetic energy of the particles in a substance, typically measured in degrees Celsius (°C) or Kelvin (K).

Specific Heat Capacity (c)

The amount of energy required to raise the temperature of 1 kg of a substance by 1 °C, measured in J/(kg⋅°C).

Thermal Equilibrium

The state in which two objects in thermal contact no longer exchange heat energy because they are at the same temperature.

Heat Transfer

• Conduction: Transfer of heat through direct contact of particles in a solid or stationary fluid.
• Convection: Transfer of heat by the movement of a fluid (liquid or gas).
• Radiation: Transfer of heat through electromagnetic waves, such as infrared radiation, without the need for a medium.

Specific Heat Formula

Formula

$Q=mc\mathrm{\Delta T}$

Variables

• Q: Heat energy (J).
• m: Mass of the substance (kg).
• c: Specific heat capacity (J/(kg⋅°C)).
• ΔT: Change in temperature (°C or K).

Applications of Heat and Temperature

• Boiling water: Energy is transferred as heat to raise the temperature of the water to its boiling point.
• Cooking: Conduction transfers heat to food through contact with hot surfaces.
• Weather patterns: Convection drives air movement in the atmosphere, influencing weather and climate.

Questions for Students

1. Define heat and temperature. How are they related?
2. Describe the three methods of heat transfer with examples.
3. Explain the concept of specific heat capacity and provide its formula.
4. Calculate the heat required to raise the temperature of 2 kg of water from 25 °C to 75 °C (c = 4,186 J/(kg⋅°C)).
5. What happens to two objects in thermal contact when they reach thermal equilibrium?