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# Physics :)

Physics mind map Heat tansfer process .
by

## Kaman Cheng

on 27 January 2013

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#### Transcript of Physics :)

Heat transfer process :D Physics Heat is the energy transferred
between two object
because of Temperature Difference. Conduction Putting hands above fire SUN Radiation - Conduction and convection require a require a
also good emitters. What is Heat? - Heat always flows from a higher temperature body to a
lower temperature body.
- The lower temperature body increasing the internal energy
because it is receiving the heat.
- No heat flows if two bodies have same temperature
(Thermal Equilibrium)
- The rate of heat transfer depends on the temperature driving force, the area available for heat transfer, the nature of the material and the mode of heat transfer
(conduction, convection or radiation). Convection holding the metal part of BBQ fork Convection - Heat can be transferred though movement of hot matter. - When the temperature of air the volume - This make it less dense. - The warm air floats upwards through the denser
cooler air around it. Being less dense, This method of heat transfer is called Convection - When warm air cooler air moves in to take its place. - The result is a circulating current of air called the convection current. - Convection can occur in all gases and liquids. Conduction Example Convection Conduction - Conduction can occur inside an objects /
between two objects in contact in which
energy is transferred from a higher temperature
region to a lower temperature region, - Molecules in the part of a body at a higher temperature vibrate faster , therefore they have higher KE -Molecules in the part of a body at a lower temperature vibrate slower , therefore they have lower KE Conduction - Molecules with higher K.E collide to molecules with lower K.E - K.E of molecules in a region of lower temperature will be and then the temperature of that region will Bad Conductor:
non-metals, Wood, Plastic, Gas Good Conductor:
Metals, Iron ,Copper Radiation earth radiation - Radiation transfer energy by electromagnetic waves. - Visible radiation is emitted from the burning material, but most of heating effect comes from the invisible
infrared radiation emitted by the hot and warm objects Dull black surfaces are the best absorbers of radiation
The absorb most of the radiation . Shiny silvery surfaces are the worst absorbers of radiation.