GCSE AQA energy topic 1

what are the eight energy stores

thermal, kinetic, gravitational potential, elastic potential, chemical, magnetic, electrostatic, nuclear

how is energy transferred

mechanically, electrically, heating, radiation

what is a system

An object or group of objects

what happens when a system is changed

Energy is transferred

what is a closed system

a system where neither matter nor energy can enter or leave

what is work done

energy transferred

what happens when you throw a ball

the initial force exerted by a person to throw a ball upwards does the work. it causes an energy transfer from the chemical energy store of the person's arm to the kinetic energy store of the ball or arm

what happens to a ball when dropped

a ball dropped from from a height is accelerated by gravity. the gravitational force does work causing energy to be transferred from the balls gravitational potential energy store its kinetic store

what happens when a cars slowing down

the friction between a cars wheels and breaks does work as it slow down. it causes energy transfer from the wheels kinetic energy store to the thermal energy stores surroundings

what is a kinetic energy store

anything moving has energy in its kinetic energy store

what does the energy in a kinetic energy store depend on

the object's mass and speed

what is the gravitational potential energy store

Anything in a gravitational field (anything that can fall)

what does the gravitational potential energy depend on

an objects mass height and strength of gravitational speed

what is the elastic potential energy store

the energy stored when an object is stretched or squashed.

why can't the equation for elastic potential energy always be calculated

it can only be calculated as long as the limit of proportionality hasn't been reached

what is specific heat capacity

the amount of energy required to increase the temperature of 1kg of a substance by 1oC

what is the law of conservation of energy

energy cannot be created or destroyed

what is dissipated energy

wasted energy because the energy is being stored in a way that is not useful.

what is power

the rate at which energy is transferred (rate of doing work)

what is one watt equal to

one joule of energy transferred per second

what is conduction

the process where vibrating particles transfer energy to neighbouring particles

describe what happens during conduction when an object is heated

when heated particles in the object vibrate more and collide with one another. these collisions cause energy to be transferred between particles kinetic energy stores. this is conduction. the process continues until it is the same temp everywhere

What is convection?

when energetic particles move away from hotter to cooler regions

describe what happens during convection (in depth)

the particles in liquid and gases are able to move to move so when you heat an object space between particles increase causing the density of the region being heated to increase. the warmer less dense dense regions rise above cooler denser regions. if there's a constant heat source convection currents can be created

when are convection currents used

in radiators.

how do radiators use convection currents

energy is transferred from the radiator to nearby air particles by conduction so the air by the radiator becomes warm and less dense. the warm air rises and is replaced by cooler air which is heated. at the same time previously heated air transfers energy to the surroundings and then becomes cooler less dense and sinks. the cycle repeats and the flow of air is a convection current

what do lubricants do?

reduce frictional forces

how can energy loss be reduced

-thick walls made from material with low thermal conductivity
-use thermal insulation including: cavity walls, cavity wall insulators, loft insulation, double glazed windows, draught excluders

what is a useful device?

an object that transfers energy usefully (less energy wasted)

what are the three main fossil fuels

coal, oil, natural gas

What are renewable energy sources?

the sun, wind, water waves, hydro-electricity, bio-fuel, tides, geothermal

why are renewable resources good

-never run out
-most of them damage the environment but not as badly
-dont provide much energy

how does transport use non renewable energy

-petrol and diesel powered vehicles
-coal in Old fashioned steam trains

how does transport use renewable energy

vehicles that run on pure biofuel or a mix of biogul and petrol/diesel

how does heating use non-renewable energy

-natural gases widely used to heat homes
-coal burnt in fireplaces
-electric heaters which use electricity generated from non renewable energy sources

how does heating use renewable energy sources

-geothermal heat pump to heat buildings
-solar water heaters to heat water used in radiators
-burning bio fuel or using electricity generated from renewable sources

how does wind power generate energy

it uses lots of wind turbines in exposed places. each turbine has a generator that turns to produce electricity

what are the positives of wind power

there are no fuel costs and minimal running costs and there is no pollution created (except for manufacturing)

what are the negatives of wind power

can be noisy
need 1500 to equal one coal powered power station
can be an eyesore
initial manufacturing and installation costs are high
unreliable source of energy

how so solar cells generate electricty

they generate electric currents directly from sunlight

what are the positives of solar cells

-no pollution
-in sunny countries is reliable and still cost effective in cloudy countries
-low running costs

what are the negatives of solar cells

-create pollution when manufacturing
-only reliable during daytime
-cant increase power output
-initial cost is high

how does geothermal energy work?

in some volcanic areas hot water and steam rise to the surface, the steam can be tapped and used to drive turbines

what are the positives of geothermal energy

free and reliable
little damage to the environment

what are the negatives of geothermal energy

-only available in certain areas
-cost of building is high

What is hydroelectric energy?

flooding of valley by building a big damn. water is allowed through turbines

what are the positives of hydroelectricity

-immediate response to increased demand
-only problem with reliability is if there's a drought, unlikely in England
-no fuel cost and minimal running cost

what are the negatives of hydroelectricity

-big impact on the environment. loss of habitat and vegetation
-initial high cost

what is wave power

lost of wave powered turbines around the coast connected to generators

what are the positives of wave power

-no pollution
-useful on small islands
-good for producing energy on a small scale
-low running costs

what are the negatives of wave power

fairly unreliable
doesn't provide a lot of energy
hazardous to boats and nature
high initial costs

What are tidal barrages?

Big dams built across river estuaries, with turbines in them. as the tide comes in it fills up the estuary. water is then allowed out by turbines at a controlled speed. tides are produced by the gravitational pull of the sun and moon

what are the positives of tidal barrages

-no pollution
-pretty reliable as tides happen twice a day
-no fuel costs and minimal running costs
-can generate a significant amount of energy

what are the negatives of tidal barrages?

-prevents free access by boats
-spoil the view
-alters habitat of wildlife
-if the height of he tide is lower less energy is produced
-they don't work when water levels are the same either side of the barrage

what are bio fuels

renewable energy resources created from either plant products or animal dung

what are the positives of bio fuels

-supposedly carbon neutral
-fairly reliable

what are the negatives of bio fuels?

-debate of whether they're actually carbon neutral because its only true if you burn things at the rate you grow them
-cant responds to immediate demand
-high cost
-growing takes up growing space for food
-large areas of forest have been cleared to make room for growing which destroys habitats

What are positives of non-renewable energy resources?

-they can meet demand
-running costs aren't expensive
-reliable
-power plants always have fuel in stock

what are negatives of non renewable energy sources

-slowly running out
-set up costs are high

what are the environmental problems with fossil fuels

-they release CO² into the atmosphere when burned
-releases sulfur dioxide which causes acid rain
-coal mining makes a mess of the landscape
-oil spillages can cause serious environmental problems
-nuclear power is clean but nuclear waste is difficult to dispose of and dangerous

why don't companies want to switch to renewable energy sources

because it costs a lot of money to switch to renewable energy sources.