P2 - Thermal physics (kinetic particle model of matter, thermal expansion, boiling and evaporation, convection, conduction, radiation and their consequences) Flashcards
process of solid to liquid
melting
process of liquid to gas
boiling/ evaporation
process of gas to liquid
condensation
process of liquid to solid
freezing
process of solid to gas
sublimation
process of gas to solid
deposition
particle arrangement and motion in solid
-lattice structure with closely and motion in packed and motion in particles that vibrate in fixed positions
particle arrangement and motion in liquids
-irregular order of particles that move around each other randomly
particle arrangement and motion in gas
-irregular order of particles that move around freely and randomly in all directions.
compressible- solid, liquid, gas
solid- no
liquid- no
gas- yes
space between particles in solid, liquid, gas
solid- no
liquid- yes, little
gas- yes lots
change in substance volume
solid- no
liquid- no
gas- yes
particle energy in solids, liquids, gas
solid- least
liquid- intermediate
gas- most
what happens to a heat curve on a graph
-temperature stays constant when changing state till all particles are same state.
intermolecular forces in solid, liquid, gas
solid- strong
liquid- weak
gas- negligible
define heat
amount of thermal energy
define temperature
average kinetic energy of particles
define Brownian’s motion
zig- zag motion of particles when suspended in fluid as a result of collision of particles in fluid.
2 example of Brownian’s motion
-smoke particles
-pollen grain
what is the relationship between the intermolecular forces and temperature of particles
decreases intermolecular forces, increase temperature
what is pressure in container
force of particles colliding on the wall of the container
where is pressure same in
all directions
what is the relationship between temperature and pressure
increase temperature, increase pressure
what is the relationship between volume and pressure
increase volume, decrease pressure
what is the relationship between volume, temperature and pressure
- increase volume, increase temperature, constant pressure
formula of pressure in liquids
P = hpg
pressure = height x density x gravitational field strength
formula of pressure in solids
P = F/ A
Pressure = force/ area
define expansion
particles gain thermal energy which is converted into kinetic energy to intermolecular forces and move apart
most to least expansion in matter
-gas
-liquid
-solids
expansion and contraction in power lines
-causes slack E
-snaps C
expansion and contraction in thermometer
-increase KE, increase volume, liquid rises E
-decrease KE, decrease volume, liquid falls C
expansion and contraction in bridges
-rollers help to fill small gap E
-rollers pull back C
expansion and contraction in railway
-get wonky E
-break C
define absolute 0
-when particles have no kinetic energy = no movement
-measured in kelvin
expansion and contraction in hot air balloon
-get bigger and rises E
-get smaller and falls
expansion and contraction in thermostat
-metal bends and breaks circuit when too hot E
-metal goes back to original position and completes circuit C
why does metal bar expand when heated
kinetic energy overcomes intermolecular forces
what is 0 K in celcius
0k = -273 C
why do metal bars expand when heated
KE overcomes intermolecular forces so particles can move apart
why do cables hang with slack
they don’t snap when contracting
Why don’t you reinforce concrete with Al rods
Al will expand and breaks concrete
why do bimetallic strips bend with heated
-one of the metals expands more and pushes the other one so both metal strips bend
why does water expand when freezing
-no KE to overcome Hydrogen bonds so it goes back to its regular structure
why is mercery used in thermometers
-expands easily
-volume increases with expansion
what are used in thermometers
-ethanol with red dye
-mercury
which direction is the transfer of heat and when does it stop
hot to cold until both temperatures are equal
why are metal good conductors of heat
-particles collide to transfer energy
-mobile electrons can carry energy through the structure
what do good conductors of heat do
-gain and lose heat easily
when does boiling/ evaporation happen
boiling- fixed temperature
evaporation- any temperature
how fast is the process of boiling/ evaporation
boiling- quick process
evaporation- long process
where in the liquid does boiling/ evaporation happen
boiling- throughout liquid
evaporation- at surface of liquid
are bubbles formed in boiling/ evaporation
boiling- yes
evaporation- no
how does the temperature in boiling/ evaporation remain
boiling- constant
evaporation- may change
how is energy supplied in boiling/ evaporation
boiling- heat source
evaporation- environment
what does evaporation cause and how
-cooling
-evaporated particles carry energy so the body loses energy and feels colder
what is cold
absence of heat
4 factors of evaporation
-temperature
-humidity
-surface area
-wind speed
what is humidity
amount of water vapour in air
what is the relationship between humidity and evaporation
increase humidity, decrease evaporation
3 examples of cooling through evaporation
-coming out of hot shower
-washing face
-drying clothes
3 energy transfers
-conduction
-convection
-radiation
define conduction
transfer of energy through collision of particles
describe conduction is solids
particles vibrate and collide with each other to transfer energy
describe conduction in gas
particles collide with each other to transfer energy
describe conduction in liquids
particles collide with each other to transfer energy
best to worst state of matter for conduction and why
-solid- closely packed together
-liquid
-gas- particles are far apart
define insulators
poor conductors of heat eg. air, wood, plastic
define convection
transfer of energy in fluids by creating a convection current where less dense hot particles rises and more dense colder particles sinks
which states of matter are fluids
liquids and gas
why is convection only in fluids
they have to to free to move and set up a convection current
which is the best state of matter in convection and why
-liquids- particles are close to each other
what must you do when drawing a convection current
draw 2 arrows to show the convection current
what does the sea have more than the land
a larger thermal capicity
what is an onshore breeze
-at day
-land loses heat, convection current, breeze to the land
what is an offshore breeze
-at night
-water loses heat, convection current, breeze to water
why is wood a good insulator
there is poor transfer of energy between particles
why is it safer to touch hot stuff with a dry cloth than a wet cloth
-wet cloth has solids and liquids so it transfer heat through conduction and convection
-dry cloth has only solid so it only transfers heat through conduction
why is a drought felt near a bon fire
the air from convection current comes past
why cant a fridge cool the food if it is tightly packed together
no air particles to do conduction or convection
define radiation
transfer of energy by a wave
where does radiation occur
solid, liquids, gas, vacuum
what does a wave contain
-visible light
-inferred light
what can be done to a wave
reflected, absorbed, transmitted, emitted
define emission
wave is given out
define transmission
traveling through a medium
what is transmission same in
same materials
rank best to worst reflectors
-shiny silver
-white
-glossy back
-matt black
rank best to worst emitters
-matt black
-glossy black
-white
-shiny sliver
rank best to worst absorbers
-matt black
-glossy black
-white
-shiny sliver
which state of matter is radiation best in
-gas- particles are far apart so there are less collisions for the wave and it can travel easily
5 ways to reduce heat loss from house
-double glazed windows
-wooden door with foam strips
-wool under roof
-carpet on floor
-curtain on walls
2 main greenhouse gases
-methane
-carbon dioxide
biggest contributors to the production of greenhouse gases
-methane - cows and sheep’s burps, decomposition
-carbon dioxide - respiration, combustion of fossil fuels
define global warming
-average temperature of the earth increasing
define climate change
-long term changes of climate
define the greenhouse effect
the earth’s atmosphere traps heat
4 examples of climate change
-(unpredictable weather patterns)
-floods
-hurricanes
-forest fires
-soil erosion
why is vacuum flask a good product
-cork stopper: insulator to prevent conduction from the top
-insulated support: insulator to prevent conduction from the bottom
-vacuum: prevents conduction and radiation- only radiation comes through
-shiny silver layer inside: good reflector of radiation
how does the shiny silver layer in the vacuum flask work
-heat moves from hot to cold
-good reflector of radiation from outside for cold water
-good reflector of radiation from inside for hot water
