Fichas
Physics Unit 1 - Heat transfer
Fichas del conjunto (19)
- 1how is heat energy transfered in solids?by conduction, the particles vibrate and the heat spreads along
- 2how is heat energy transfered in gases & liquids?through convection, the particles colliding
- 3what is emitted by solids, gases and liquids?infrared radiation
- 4what happens if the temperature difference is big between a body and its surroundings?the heat energy transfer is quicker
- 5what type of objects emit (give out) more infrared radiation? and which ones absorb more?those hotter than their surroundings emit more and those cooler absorb more
- 6what type of surfaces absorb radiation best and what type emit radiation best?absorb - matte dark materials
emit - light shiny white/silver materials
hence why solar panels are dark panels on top of water pipes, so they absorb the heat to warm the water up - 7What happens when you heat a substance?it gains more kinetic energy, so its particles can vibrate or move more which is what causes solids to melt, and liquids to boil
- 8Why are metals good conductors?because there free electrons allow the heat to be spread not just by vibration but by the electrons spreading the heat
- 9what solid materials are not so good at conducting?stuff like polystyrene because the particles are really spaced out so they can't vibrate to spread heat
- 10Describe how conversion works in the Immersion Heater- heat energy is transferred from the hot bit (radiator type thing) to the water by particle collisions
- the particles now move quicker and space out so the water expands and becomes less dense, so the hotter water rises and the denser cooler water sinks.
- The hot water has "displaced" the cool water"
- at the bottom, the cool water is now re-heated by radiator thingy - 11where does convection work best?in squarish or roundish containers because tall and thin ones don't have the space to allow the particles to spread out which means the cold particles hit the warm and vice versa so convection currents cant be created
- 12what are convection currents?changes in density
- 13what are other examples of convection?radiators with cool air in a room sinking, and hot air rising
- 14Describe condensationWhen the particles in a gas come into contact with a cold surface or surroundings so they lose kinetic energy and start to move closer together causing them to turn into a liquid
- 15Describe EvaporationWhen particles from a liquid escape, they gain a lot of kinetic energy either through an increase of temperature or they are luckily travelling in the right direction, or they are moving fast enough or overcome the other particles attractive forces. When they escape the other liquids particles cool down, like when you sweat the water on your skin evaporates and you cool down.
- 16How can you make the rate of evaporation slower?-decrease the temperature
- if the density is higher, this will make the particles more attracted to each other so its harder to escape
- surface area is smaller, less particles will be close to the surface area to evaporate into the air
- less airflow over the liquid, if too many particles have already evaporated, its really difficult for others too, so if there is less warm air for the liquid to reach then evaporation slows down. - 17How to slow down the rate of condensation?-increase the temperature of the gas, so the particles move quicker and don't slow down to condense
- increase the temperature of the surface or surroundings
- density is lower, the more space for the particles to move around
- airflow is more, if the cool air around it will keep the particles cool - 18what affects the rate of energy transfer?-a bigger surface area allows more infrared waves to be emitted or absorbed by the object
- a smaller volume because more of the particles are in touch with the surroundings
- insulators emit heat slower than conductors - 19what objects give us examples of heat transfer?computers have fins to give out heat so they don't overheat and damage, they have a high rate of energy transfer, so do car engines
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- Descripción
- GCSE (Physics Core) Science Fichas sobre Physics Unit 1 - Heat transfer , creado por pwincessria el 12/04/2015.
- Creado por
- pwincessria · abr 2015
- Actualizado
- 7 mar 2018
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