3.3 conservation of energy / 3.4 moving from hot to cold / 3.5 ways of transferring thermal energy

law of conservation of energy

energy cannot be created or destroyed, only changed or transferred

what is dissipation used to describe

energy that spreads out and becomes less useful

what are the ways of transferring thermal energy

conduction, convection, radiation

particle theory of solids

• the solid particles move by vibrating in a fixed position.

• when particles vibrate more vigorously, they take up more space

• solids expand when heated.

particle theory of liquids

• particles vibrate, but are not in fixed positions.

• when liquid is heated, particles vibrate faster and move faster

• particles take up more space

• liquid exapnds when heated

particle theory of gas

• particles are far apart and move in straight line until they collide with another particle or with the walls of the container it is in

• when heated, particles move faster and collide with more force and more frequently

• particles take up more space

• expands when heated

process of conduction

heat transfers from hotter region to colder regio through solid medium when in contact by vibrations

process of convection

process of heat transfer from hotter region to colder region through fluids (gas or liquid). the particles move freely and carry thermal energy with them.

what happens to the fluids (cold & hot) of convection when heated?

the hotter fluid expands and becomes less dense and rises. colder fluid becomes denser and goes down by replacing the empty space left by hot fluids

what are the circulating movement of the fluids that rise and fall called

convection current

process of radiation

flow of heat from a source of heat to its surrounding with gas particles or without any medium (vacuum)

what affecs the process of radiation (rate of heat flow)

type of srface, temperature, surface area of object