Heat & Thermal Physics
The dynamics of thermal energy transfer and temperature.
Heat is the transfer of thermal energy between systems due to a temperature difference. Temperature measures the average kinetic energy of molecular motion.
This unit covers calorimetry (specific heat, latent heat of phase changes), the three mechanisms of heat transfer, and thermal expansion of solids.
Key Takeaways
- •Heat flows spontaneously from regions of higher temperature to lower temperature.
- •Phase changes occur at constant temperature, absorbing or releasing latent heat.
- •Most materials expand when heated because molecular kinetic motion pushes atoms apart.
Core Concepts & Definitions
1Specific Heat Capacity
The amount of heat energy required to raise the temperature of 1 kg of a substance by 1°C (or 1 K).
•Q = m * c * ΔT, where c is the specific heat capacity.
•Water has an exceptionally high specific heat capacity (4186 J/kg·K).
2Latent Heat & Phase Changes
The heat absorbed or released during a change in state (solid-liquid-gas) without changing temperature.
•Q = m * L, where L is the Latent Heat of Fusion or Vaporization.
•The plateau regions on heating curves correspond to phase transitions.
Quick Revision Notes
- •Temperature does not change during a phase change; the heat energy goes into breaking intermolecular bonds.
- •Conduction operates primarily in solids; convection operates in fluids (liquids/gases).