Thermal Physics and Heat Transfer
Temperature vs Heat
Core distinction
Temperature measures average microscopic kinetic energy, while heat is energy transferred because of a temperature difference. Heat flows spontaneously from hotter to cooler regions.
Important distinction
Temperature is not energy. A small hot object and a large warm object can contain very different amounts of thermal energy.
Specific Heat and Phase Change
Heating relation
Thermal energy change can often be modeled by . During a phase change, energy goes into changing state rather than temperature, so is used instead.
What happens during melting at the melting point?
Added energy changes the material’s phase, so temperature remains constant until the transition is complete.
Correct answer: Temperature stays constant while phase changes
What does specific heat capacity tell us?
It quantifies how resistant a material is to temperature change.
Correct answer: How much energy is needed to raise temperature by 1 degree per unit mass
Heat Transfer Mechanisms
Modes of heat transfer
Conduction
- Energy transfer through direct contact
- Important in solids and thermal interfaces
Convection
- Energy transfer by moving fluid
- Important in air and liquids
Which heat transfer mechanism can occur in a vacuum?
Radiation transfers energy by electromagnetic waves and does not require a material medium.
Correct answer: Radiation
Why do insulation materials often trap air?
Trapped air slows heat transfer by limiting conduction and bulk fluid motion.
Correct answer: Air is a poor conductor and reduces convection
Engineering use
Thermal design balances conduction, convection, radiation, and material limits to control overheating or retain heat.