TSE CASSANRA'S PHYSICS PROJECT

UNIT 8 transfer of thermal energy
THREE METHODS
- conduction
-convection
-radiation

explanation of above pic:

conduction;transfer of thermal energy without any flow of material medium

when thermal energy is supplied to an end,the particles vibrate vigorously,about fixed positions, and collides with neightbouring particles,making them vibrate ( like a domino effect)thus the kinetic energy is transferred to neighbouring particles.

conduction is most efficient in metals,whereas in liquid and gases,it is inefficient because their particles are further apart as compared to solids.hence collision occurs less frequent.this is why air and water are poor conductors.

convection;transfer of thermal energy through currents of fluids(liquids and gases)

when water at the bottom of the pot is heated,it expands.The expanded water is less dense than the surrounding water,hence it rises,leaving the cooler water at the upper parts of the pot,to sink being denser.thus a movement(current) is formed due to the difference in its density.

convection can only take place in fluids!TIB(this is because) convection requires bulk movement of fluids,but solids can only vibrate about in fixed positions and are unable to move in bulks.

radiation;a continuous emission of infrared waves from the surface of all bodies,transmitted without the aid of a medium.(can take place in vacuum)

(click for larger image)

the heat that reaches the Earth from the Sun,is done so byt the process of radiation.Convection and conduction are impossible because of the vacuum between Earth and the Sun.

ALL OBJECTS absorb and emmit some radiant heat.
the hotter the object the greater amount of radiant heat.

all objects and surfaces absorb infrared radiation.the absorption causes temperature to rise

-dull,black surfaces absorb infrared radiation faster compared to shiny white surfaces.
-dull black surfaces are better emitters of infrared radiation than shiny white surfaces

factors affecting rate of infrared radiation.
colour- dull black surfaces are better absorbers and emitters of infrared radiation

surface temperature-the higher the temperature of the surface to the surrounding temperature,the higher the rate of infrared radiation

surface area-comparing two objects of equal weight and mass,the object with a larger surface area will emit infrared radiation at a higher rate

VIDEO TIME!

conduction

convection

radiation


Thursday, September 4, 2008 UNIT 8 transfer of thermal energy THREE METHODS - conduction -convection -radiation explanation of above pic: conduction;transfer of thermal energy without any flow of material medium when thermal energy is supplied to an end,the particles vibrate vigorously,about fixed positions, and collides with neightbouring particles,making them vibrate ( like a domino effect)thus the kinetic energy is transferred to neighbouring particles. conduction is most efficient in metals,whereas in liquid and gases,it is inefficient because their particles are further apart as compared to solids.hence collision occurs less frequent.this is why air and water are poor conductors. convection;transfer of thermal energy through currents of fluids(liquids and gases) when water at the bottom of the pot is heated,it expands.The expanded water is less dense than the surrounding water,hence it rises,leaving the cooler water at the upper parts of the pot,to sink being denser.thus a movement(current) is formed due to the difference in its density. convection can only take place in fluids!TIB(this is because) convection requires bulk movement of fluids,but solids can only vibrate about in fixed positions and are unable to move in bulks. radiation;a continuous emission of infrared waves from the surface of all bodies,transmitted without the aid of a medium.(can take place in vacuum) (click for larger image) the heat that reaches the Earth from the Sun,is done so byt the process of radiation.Convection and conduction are impossible because of the vacuum between Earth and the Sun. ALL OBJECTS absorb and emmit some radiant heat. the hotter the object the greater amount of radiant heat. all objects and surfaces absorb infrared radiation.the absorption causes temperature to rise -dull,black surfaces absorb infrared radiation faster compared to shiny white surfaces. -dull black surfaces are better emitters of infrared radiation than shiny white surfaces factors affecting rate of infrared radiation. colour- dull black surfaces are better absorbers and emitters of infrared radiation surface temperature-the higher the temperature of the surface to the surrounding temperature,the higher the rate of infrared radiation surface area-comparing two objects of equal weight and mass,the object with a larger surface area will emit infrared radiation at a higher rate VIDEO TIME! conduction convection radiation Oh yes, I did @ 10:58 PM.	EHEM howdy,this is my thermal physics project Tse (36) TAG-BOARD CREDITS Design/Layout: Naziz