Heat Transfer and Thermal Equilibrium
Introduced| English |
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| thermal equilibrium/ˈθɜːml ˌiːkwɪˈlɪbrɪəm/ |
Warm meets cold
- Drop an ice cube in warm tea and both change.
- The tea cools; the ice warms -- they meet in the middle.
- Something always flows from the hotter to the colder.
- Eventually everything settles at one temperature.
Heat flows hot to cold
- Heat always flows from the hotter object to the colder one.
- It never flows the other way on its own.
- The hot thing cools while the cold thing warms.
Heat flows from...
Heat always flows from the hotter object to the colder one.
Settling at one temperature
- Thermal equilibrium 热平衡 is when both reach the same temperature.
- Heat flow then stops, because no temperature difference is left.
- Everything in contact ends up equally warm.
At thermal equilibrium, two objects in contact have...
Equal temperatures mean no more net heat flow.
Net heat flow stops once the two objects reach the same temperature.
With no temperature difference, there is no driving force for heat.
Heat is not temperature
- Temperature measures the average energy of the particles.
- Heat is the energy that flows because of a temperature difference.
- A big cool object can hold more heat than a small hot one.
Reaching thermal equilibrium
Two objects at different temperatures always settle to the same temperature.
Heat and temperature are the same thing.
Heat is energy in transit; temperature is average particle energy.
A large cool object can hold more ____ than a small hot one.
Total heat depends on mass and material, not just temperature.
Hot metal is dropped into cool water. What happens?
- Heat flows from the metal to the water.
- The metal cools and the water warms until their temperatures match.
Hot metal is placed in cool water. The metal...
Heat leaves the metal and enters the water, so the metal cools.
Heat flows from hot to cold, never the reverse -- a cold object does not "send cold." Do not confuse heat (energy in transit) with temperature (how hot something is). At thermal equilibrium the temperatures are equal, so the net heat flow stops.
Heat always flows from a hotter object to a colder one, cooling one and warming the other, until they reach thermal equilibrium at the same temperature. Heat (energy in transit) is not the same as temperature (average particle energy) -- a large cool object can hold more heat than a small hot one.