Flashcards
Physics unit 1
Flashcards do conjunto (41)
- 1What are the three ways that heat is transferred•conduction
•convection
•radiation - 2Describe conduction•occurs mainly in solids
•conduction of heat energy is when vibrating particles pass on their extra kinetic energy
• to neighboring particles until the whole solid is heated - 3What does conduction work best in•In denser solids because their particles are a lot closer (making the particles collide more)
• BUT materials that have spaced out particles conduct heat slower
[These are called insulators] - 4Why are metals good conductors?•Because of their delocalised electrons
• they can move more freely and transfer the heat quicker. - 5What is heat/ infrared radiation?A former of heat that can be emitted by solids liquids and gases
- 6Describe how texture and colour have a big influence on infrared radiation•dark matt surfaces ABSORB infrared falling on them
•BETTER than light, shiny surfaces (gloss white or silver)
• light shiny surfaces REFLECT alot of I.R falling on them.
(Eg - vacuum flask) - 7What can infrared only travel throughA vacuum I.e space (where there are no particles)
- 8Where do covenection currents happenOnly in gasses and liquids
- 9Explain a convection current in a liquid• water gets heated
• the particles gain kinetic energy and move faster
• this means they become less dense
• this causes the water to rise
• and displace the less energetic particles
• they then sink and the then gain energy and repeats
• this is called a convection current - 10Use an example to show how heat transfer is limited in a device• the glass bottle is double-walled to stop all conduction / convection currents through the sides
• the walls either side of the vacuum are Silverdale to keep heat loss by radiation to a minimum.
• the bottle is supported using insulating foam - this minimises heat conduction to or from the outerminal glass bottle.
• the stopper is made of plastic and filled with cork(or foam) to reduce any heat conduction through it. - 11Describe the process of condensation• when a gas cool, the particles in gas slow down and lose kinetic energy
• the attractive forces between the particles pull them closer
• if the temperature gets cold enough and the gas particles get close enough allowing CONDENSTATION to take place...
• the gas turns to a liquid - 12What is evaporation?When particles escape from a liquid into a gas
- 13Describe the process of evaporation• only particles at the surface of a liquid can EVAPORATE
• BUT This will only happen if the particles
: are travelling in the right direction to escape the liquid
• if the particles have enough kinetic energy to overcome the attractive forces of the other particles - 14What are the factors of evaporation ( what happens to the liquid as particles evaporate)• as the fastest particles evaporate, the remaining particles decreases
• meaning the average temperature falls
• this 'cooling effect' can be useful when your hot and sweating - 15How could you increase the rate of condensation and evaporation?EVAPORATION
• higher temp
• lower density - forces between particles will be weaker
• larger surface area
• more airflow
CONTESTATION
• temperature of the gas is lower
• temp of the surface the gas touches is low
• higher density - strengthening the forces between the particles
• airflow is less - 16Use an example to describe how heat transfer is limited in a deviceVacuum flask
• the glass bottle is double-walled with a vacuum to stop all conduction and convection through the sides
• the walls either side of the vacuum are silvered to minimise heat loss by radiation
• the bottle is supported by insulating foam to minimise heat conduction to or from the outer glass bottle
• the stopper is made of plastic and filled with cork or foam to reduce any heat conduction through it. - 17How do animals and humans control heat transfer?-HUMANS
• in the cold the hairs on your skin stand to trap a thicker layer of insulating air around your body
• when your warm your body diverts more blood flow near the surface of your skin so that more heat can be losses by radiation.
-ANIMALS
• animals in hotter climates have larger ears than those that live in colder climates to controlled thir heat transfer - 18What is a u - valueU-values show how fast heat can transfer through a material
So the better the insulater the lower the u-value - 19How do you work out the payback time?Payback time (years)=
cost of insulation(£) ÷ savings per year in fuel costs (£) - 20What is the difference between 'cost effectiveness' and 'effectiveness'?• the most cost effective tend to be the cheapest
- they have short payback times (good)
• the most effective methods of insulation give you the biggest annual saving
- so eventually the money you saved on heating bills will equal the initial cost of installing the insulation. - 21Name 9 types of energy1) electrical energy
2) light energy
3 sound energy
4) kinetic /movement energy
5) nuclear energy
6) thermol/heat energy
7) gravataional potential energy
8) elastic potential energy
9) chemical energy - 22What are kWhUnits of energy
- 23Name 4 non renewable sources of energy and there rolls• coal
• oil
• natural gas
• nuclear fuels
- all gonna run out
- all do damage to the environment
- provide us with most of our energy - 24Name 8 renewable sources of energy and there rolls• wind
• waves
• tides
• hydroelectric
• solar
• geothermal
• food
• biofules
- never run out
-they do damage but in less nasty ways
- don't provide much energy as they are unreliable - 25Describe how energy sources can be burned to drive turbines in a power station and produce electricity• the fossil fuel is burned
• to convert is stored chemical energy into heat
• the heat energy is used to heat water to produce steam
• the steam turnshower the turbine
• convertible get heat energy to kinetic energy
• turbine is connected to a generator
• which transfers kinetic energy to electrical energy - 26What is a nuclear reactorA nuclear power station that uses nuclear fission of uranium and plutonium producing the heat to make the steam and turn the turbines
• but it takes the longest to start up. - 27What are biofuels made out of and what is there use?They are made of plants and waste
• they also make electricity through the same method as fossil fuels would.
• also used in some cars - 28How are non-renewables linked to the environmental problems• fossil fuels (coal oil and gas) release co2 in the atmosphere when they're burned
• adding to the greenhouse effect and global warming
• burning coal releases sulfur dioxide which causes acid rain
• coal mining makes a mess of landscapes
• oil spillages effect mammals and birds that live around the sea
• nuclear power create a lot of dangerous waste - 29What is the national grid?It takes takes electrical energy from power stations to to where it's needed in homes and industry
- 30Describe the rolls of the pylons and transformers when electricity is passed out• to get 400000v to transmit power requires transformers as well as big pylons with huge insulators
• the transfers have to step the voltage up at one end for efficient transmission
• and then bring it back down to safety at the other end
- basically the voltage is increased (stepped up) using a step up transformers
- it's then reduced again ( stepped down) at the consumer end using stop down transformer - 31What are the differences between transverse and longitudinal wavesTransverse waves:
• light and all other EM waves
• looks like a slinky spring wiggling up and down
Longitudinal waves:
• sound waves and ultra sound waves
• a slinky spring when push one end ( it compresses ) - 32What is the law of reflection?The angle of incidence always equals the angle of reflection
- 33What is the definition of diffractionWaves spreading out, which changes depending on how big the Gap is
- 34What is the definition of refractionWhen you change the speed of a wave it can change its direction
Whether it's in air or glass. - 35sing the electromagnetic wave songRadio waves - low freq
microwaves
Infrared radiation
Visible light
ultra violet
X - RAYS
Gamma rays - high freq - 36What proves that the universe is expandingred shift
- 37What is red shift• when we look at distant galaxies we can see the same patterns but at slightly lower frequencies then they should be
• they're shifted toward the red end of the spectrum
If a galaxy is red shift it is moving away very quickly - 38What is the doppler effect?• when something that emits waves moves towards you or away from you
• the frequency of the waves seems different
• *compared to when it was stationary * - 39Describe what happens to the wavelength and frequency as a race car is moving towards and when it moves away from you.....• the frequency of it moving towards you will seem higher
• the wavelength will seem shorter
•The frequency of it moving away from you will seem lower
• the wavelength will seem Longer - 40What is the big bang theoryThe theory states that about 13.7 billion years ago all the matter in the Universe was concentrated into a single incredibly tiny point
- 41What is wrong with the big bang theory• it's not the the whole explanation of the universe
• the big batheory predicts that the universes expansion should be slowing down but actually it's speeding up
Informações
- Descrição
- Question and answers to basic topics in p1
- Criado por
- ManishaBhaker78 · mai 2016
- Atualizado
- 6 abr 2018
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