energy transfers

what is conduction?

The process where vibrating particles transfer thermal energy to neighbouring particles through collision

why do particles vibrate more when heated?

because more energy is transferred to their kinetic energy store so they vibrate more and collide with each other

what can materials with a high thermal conductivity do?

the faster energy can be transferred through it by conduction

What is convection?

Where energetic particles move away from hotter to cooler regions as they are less dense the particles around them so they rise to cooler regions and the cold air sinks as it is more dense the particles around it forming a cycle. Only occurs in fluids

What is a way of reducing unwanted energy transfers?

using thermal insulation

What do cavity wall insulations do?

using cavity wall insulation is when there is an insulative foam in-between the outer wall and the inner wall preventing heat transfer by convection in the cavity walls

what doe s loft insulation do?

uses fibreglass wool (insulative material) laid out across the whole loft floor to reduce conduction to the attic space and also reduces energy transfers by convection as it prevents convection currents from forming

what do double glazing windows do?

they have an air gap between and outer and inner window to prevent energy transfer by conduction through the windows

What does draught-proofing do?

use a strip of foam around doors and windows to stop draughts blowing in and out reducing energy transfer by convection

What is efficiency?

the percentage of the work input that becomes useful work output

what is the equation for efficiency?

efficiency = useful output energy transfer/ total input energy transfer

what are non renewable energy sources?

energy sources that are being used at the same rate that they are created and will eventually run out

what are examples of non renewable energy sources?

coal, oil, natural gas, nuclear

What are renewable energy sources?

Energy sources that can be replenished over and over again; they are never depleted (usually converted into electricity or thermal energy)

what are examples of renewable energy stores?

wind, tidal, solar, bio fuel, geothermal

what are non renewable resources used for?

transport- used as petrol and diesel, coal used in steam trains,

heating- natural gas for heating homes, oil as some places use a burning oil tank, coal for fireplaces

renewable resources uses

transport- some vehicles run on pure bio fuel or a mix of bio fuel and petrol

heating- geothermal heat pump used to heat buildings, solar water heaters used radiation from the sun to heat water which is then pumped into the building

what are advantages of fossil fuels?

High energy and power output, easily distributed, efficient, convenient, not dependant on weather

what are disadvantages of fossil fuels?

~ Release CO2 when burned => contributes to climate change

~ Release SO2 when burned => acid rain

~ Eventually gonna run out (non-renewable)

what are advantages of nuclear power?

high power to fuel ratio, low greenhouse gas emissions, reliable source of energy, not weather dependant, produces cheaper electric than fossil fuels

what are disadvantages of nuclear power?

hazardous radioactive wasted is produced which is harmful to environment and could cause genetic mutations, nuclear accidents can produce harmful levels of radiation , costly to set up, finite