all Flashcards
(49 cards)
what do all objects give off?
infrared radiation
what is the main source of infrared radiation?
the sun
how do dark matt surfaces when sun is shined on them
they absorb radiation and emit radiation.
but bad reflector
how do light shiny surfaces when sun is shined on them
they are bad at absorbing and emitters but they are good at reflecting.
can gasses be compressed?
yes
what do the properties of gases and liquids allow them to do?
flow
what are the volume of solid and liquid
fixed
how do you go from a solid to a liquid
put energy in by melting.
how do you go from a liquid to a gas?
put energy in by evaporating.
how do you go from a liquid to a solid?
freezing
how do you go from a gas to a liquid?
condensing
what is conduction?
is the process where vibrating particles pass their extra kinetic energy to neighbouring particles. In a solid only.
how does conduction work?
particles collide which transfers heat energy in a form kinetic energy from one end to the other end.
in a metal, why does conduction happen quicker?
it has free electrons allowing the heat to spread quicker.
where does convection occur?
fluids only. liquid or gas
what is convection?
convection occurs when more energetic particles move from the hotter region to the cooler region, and take their heat energy with them.
how does convection work?
a fluid gets heated up which causes particles top move and the particles collide which makes them become less dense. as they become less dense they start to rise which means they are not being heated anymore resulting in them having less energy. this means they start to become more dense and fall. as they fall they go back to the begging to form a convection current. the more dense particles will become heated up again to make them less dense and rise again.
what does dense mean
how close together particles are
6 steps of convection
1- water heats 2- hot water is less dense 3- less dense water rises 4-faster moving particles collide with slow moving particles causing them to transfer heat 5- water cools and becomes more dense 6 -denser water sinks again.
what is condensation
when a gas turns to a liquid
how does condensation work?
when a gas cools the particles slow down and lose kinetic energy, which bring them closer together. if the temperature gets cold enough and the gas gets close enough together condensation can take place. water vapour in the air condenses when it comes into contact with a cold surface
what is evaporation?
when a liquid turns to a gas.
how does evaporation work?
particles need to have enough kinetic energy to overcome the attractive force of other particles in the liquid and to be facing out of the liquid to escape. The fastest particles escape meaning as more particles escape the average speed and kinetic energy of the particles decrease so the temperature of the liquid decrease.
why is the cooling effect of evaporation effective?
as you sweat, the sweat on your skin evaporates causing your body to cool down.
