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What is heat?
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Quick answer
Heat is energy that flows from a hotter object to a cooler one because of their temperature difference. It's the transfer of thermal energy — the energy of moving particles — and it always moves from hot to cold until temperatures even out.
Key things to understand
- Heat is energy in transit, flowing from higher to lower temperature.
- It's different from temperature: temperature measures how hot something is; heat is the energy that moves.
- Heat transfers three ways: conduction (contact), convection (moving fluids), and radiation (waves).
- Adding heat usually raises temperature or changes state (melting, boiling).
- Heat always flows hot → cold until both reach the same temperature (thermal equilibrium).
People also ask
What's the difference between heat and temperature?
Temperature measures how hot or cold something is (the average energy of its particles); heat is the total thermal energy that flows between objects of different temperatures. A spark is hot but carries little heat.
How does heat move?
Three ways: conduction (direct contact, like a pan handle warming), convection (warm fluids rising, like boiling water), and radiation (waves, like the Sun's warmth reaching us).
Does cold flow, or just heat?
Only heat flows — always from hot to cold. 'Cold' is just the absence of heat; something feels cold because heat leaves your hand and flows into it.
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