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F4a • Unit 1
9 Concepts

Heat and Gases

Unit Overview

This topic examines the concept of thermal energy and transfer processes which are crucial for the maintenance and quality of our lives. Particular attention is placed on the distinction and relationships among temperature, internal energy and energy transfer. Students are also encouraged to adopt microscopic interpretations of various important concepts in the topic of thermal physics. Calculations involving specific heat capacity will serve to complement the theoretical aspects of heat and energy transfer. The practical importance of the high specific heat capacity of water can be illustrated with examples close to the experience of students. A study of conduction, convection and radiation provides a basis for analysing the containment of internal energy and transfer of energy related to heat. The physics involving the change of states is examined and numerical problems involving specific latent heat are used to consolidate the theoretical aspects of energy conversion. The ideal gas law relating the pressure, temperature and volume of an ideal gas was originally derived from the experimentally measured Charles’ law and Boyle’s law. Many common gases exhibit behaviour very close to that of an ideal gas at ambient temperature and pressure. The ideal gas law is a good approximation for studying the properties of gases because it does not deviate much from the ways that real gases behave. The kinetic theory of gases is intended to correlate temperature to the kinetic energy of gas molecules and interpret pressure in terms of the motion of gas molecules.

Key Concepts

1

Temperature, Thermometers and the Celsius Scale

溫度、溫度計與攝氏溫標

What temperature measures at the macroscopic and molecular level, how thermometers use temperature-dependent properties, and how we use degrees Celsius (°C).

!
Common Pitfall“Temperature is the same thing as heat or internal energy”
2

Heat and Internal Energy

熱與內能

Heat as energy transferred because of a temperature difference, and internal energy as the total microscopic energy of a system (kinetic + potential of molecules), depending on mass, temperature, and state.

!
Common Pitfall“An object ‘contains heat’ like a fluid stored in a tank”
3

Heat Capacity and Specific Heat Capacity

熱容量與比熱容

How much energy is needed to change an object’s temperature: heat capacity C = Q/ΔT and specific heat capacity c = Q/(mΔT), including why water’s high c matters and how to solve calorimetry-style problems.

!
Common Pitfall“Higher specific heat means the substance is always hotter”

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Locked Topics
  • Conduction, Convection and Radiation
  • States of Matter, Melting and Boiling Points
  • Latent Heat and Specific Latent Heat
  • Evaporation and the Cooling Effect
  • + 2 more topics

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