sec 2 science chap 10: transfer of thermal energy

In what region does thermal energy transport from?

energy will transfer from a hotter region to a colder region until both regions are the same temperature

what are the 3 ways of energy transfer?

conduction, convection and radiation

what matter does conduction occur

solids, liquid and gas

conduction cannot take place in?

vacuum

conduction definition

transfer of thermal energy without movement of the medium

what is the main mechanism in conduction?

atomic or molecular vibrations

does particles move during conduction

particles don't move

conduction moves faster in?

solids than liquid or gas and faster in metals

how to ans a question regarding to conduction?

When one end of an object is heated, the particles at this end gain kinetic energy and vibrate faster. These particles collide with their less energetic neighbouring particles and transfer the energy. In this way, heat (in terms of kinetic energy) is passed along the medium by the vibrating particle. There is no net movement of particles during the process of conduction.

convection definition

transfer of thermal energy by movement of the medium

what matter does convection occur?

occurs in liquid and gases only.

how does thermal energy transfer in convection?

 transfer of thermal energy through the bulk movement (due to changes in density) of the medium.

dooes the particles move in convection?

particles in convection move

cycle of convection

change in volume -> change in density -> movement of medium -> cycled formed

radiation definition

transfer of thermal energy in the form of infrared waves

does the objects radiate heat in radiation?

all objects radiate heat, but to different extents

good radiators?

 black, dull, rough which are also poor reflectors

poor radiators?

 white/silver, shiny, smooth which are also good reflectors

what is the ONLY process that be occur in vacuum?

radiation

what are the Factors affecting rate emission and absorption of infrared radiation

surface area, surface temperature, nature of its surface

surface temperature definition

An object with a higher temperature will emit infrared radiation at a higher rate

surface area definition

 A larger surface area emits/absorbs more infrared radiation.

nature of its surface definition

Dull and black surfaces are better emitters and absorbers of infrared radiation than shiny and silver surfaces.

thermal equilibrium definition

When an hot object is placed next to a cold object, there is a net transfer of thermal energy from the hot object to the cold object.

-The objects are said to be in thermal equilibrium when the net transfer of thermal energy stops. At thermal equilibrium, the objects have the same temperature.