Topic 1 Energy GCSE physics Flashcards
(74 cards)
1
Q
What are the energy stores?
A
thermal, kinetic, gravitational potential, elastic potential, chemical, magnetic, electrostatic, nuclear (energy stores)
2
Q
What are the ways energy is transferred?
A
mechanically (by force doing work), electrically (work done by moving charges), heating/radiation
3
Q
What happens when a system changes?
A
- energy is transferred
- it can be transferred into or away from the system
- between different objects in the system or between different types of energy stores
4
Q
What are closed systems?
A
- systems where neither matter nor energy can enter or leave
- net change in total energy is always zero
5
Q
When can work be done?
A
- when current flows
6
Q
How does energy transfer when a person throws a ball?
A
- initial force exerted by a person to throw a ball upwards does work
- causes an energy transfer from the chemical energy store of the persons arm to the kinetic energy store of the ball and arm
7
Q
How does energy transfer when a ball is dropped from a height?
A
- accelerated by gravity
- gravitational force does work
- energy transferred from balls gravitational potential energy store to its kinetic energy store
8
Q
How does energy transfer between a cars breaks and its wheels?
A
- friction between break and wheels does work as it slows down
- energy transfer from wheels kinetic to thermal energy stores of the surroundings
9
Q
How is energy transferred during a collision between the car and a stationary object?
A
- normal contact force between car and the object does work
- causes energy to be transferred from the cars kinetic energy to other energy stores
(elastic potential and thermal of object and car body)
10
Q
What is the conservation of energy principle?
A
- energy can be transferred usefully, stored or dissipated but can never be created or destroyed
11
Q
Is all of the energy transferred between stores useful?
A
- not all energy is transferred usefully
- some energy is dissipated
12
Q
How is energy wasted with a mobile phone?
A
- energy usefully transferred from chemical store (battery)
- some is dissipated to thermal energy of the phone (phone feels warm when you use it for a while)
13
Q
How is energy transferred in a closed system? (cold spoon)
A
- cold spoon dropped from an insulated flask of hot soup which is then sealed
- energy transferred from thermal store of soup to useless thermal energy store of spoon
- energy transfers have occurred within the system but no energy has left the system (net change =0)
14
Q
What is power?
A
- rate of energy transfer or the rate of doing work
15
Q
How can you calculate power?
A
power= energy transferred/time
16
Q
What is a “powerful machine”?
A
- one which transfers a lot of energy is a short space of time
17
Q
Where does conduction mainly occur?
A
- in a solid
18
Q
What is conduction?
A
- conduction is the process where vibrating particles transfer energy to neighbouring particles
19
Q
What is thermal conductivity?
A
- measure of how quickly energy is transferred through a material in this way
20
Q
Where is energy transferred to an object by heating transferred to?
A
- thermal stores of object
21
Q
What happens to the particles during conduction?
A
- particles in the part of the object being heated vibrate more and collide with each other
- collisions cause energy to be transferred between particles kinetic energy store
22
Q
Does the process of conduction continue throughout the whole object?
A
- yes
- until energy is transferred to the other side of the object
- then transferred to thermal energy stores of the surroundings
23
Q
What is convection?
A
- where energetic particles move away from hotter to cooler regions
24
Q
Where does convection occur?
A
- only in liquids and gases
25
How is convection different to conduction in terms of moving particles?
- unlike solids, the particles in a liquid are able to move
- when you heat, the particles move faster and the space between individual particles increases
26
What do radiators create?
- convectional currents
- heating a room with a radiator relies on creating convection currents in the air of the room
27
How is energy transferred in radiators?
- from radiator to nearby air particles by conduction
- air by radiator becomes warmer and less dense
- warm air rises and is replaced by cooler air
- cooler air is then heated by the radiator
28
What is a convection current (with the radiator)?
- previously heated air transfers energy to the surroundings
- it cools, becomes denser and sinks
- cycle then repeats causing a flow of air to circulate around the room (convection current)
29
What can lubricants be used for?
- reduce the friction between the objects surfaces when they move
30
What is an example of a lubricant?
- usually liquids (so they can flow easily between objects and coat them)
- oil
31
What can you do in your home to prevent energy losses through heating?
- have thick walls that are made from material with low thermal conductivity
- use thermal insulation (cavity walls, doubled-glazed windows)
32
How can you investigate the effectiveness of materials as thermal insulators?
1- boil water in a kettle, pour some into a sealable container and measure the mass of the water
2- use thermometer to measure initial temp of water
3- seal container and leave for 5 mins
4- pour water away and allow container to cool at room temp
5- repeat experiment, but wrap container in a different material
- use the same mass of water at initial temp
6- lower temp difference the better the material is as a thermal insulator
33
What is the equation for energy for energy transfer?
efficiency= useful output energy transfer/total input energy transfer
34
What is the equation of efficiency when you don't know the energy inputs?
efficiency= useful power output/total power input
35
What is an example of a device that is 100% efficient?
- electric heaters
- because all the energy in the electrostatic energy store is transferred to useful thermal energy stores
36
What the the non-renewable energy resources?
- fossil fuels and nuclear fuel
37
What are the three main fossil fuels?
- coal, oil and natural gas
38
What are the advantages and disadvantages of fossil fuels?
- will all run out one day
- all do damage to the environment
- however they are reliable
39
What are the renewable energy resources?
- sun, wind, water waves, hydroelectricity, biofuel, tides, geothermal
40
What are the disadvantages and advantages of renewable energy resources?
- never run out
- most do damage to environment, but less than non- renewable
- don't provide much energy and sometimes unreliable
41
How is non- renewable energy sources used for transport?
- petrol and diesel powered vehicles
- coal used in some old fashioned steam trains
42
How is renewable energy sources used for transport?
- vehicles running on bio-fuel or a mix of bio-fuel and petrol/diesel
43
How is non-renewable energy sources used for heating?
- natural gas for heating homes
- coal burnt in fireplaces
- electric heaters which use energy generated from non-renewable energy resources
44
How is renewable energy sources used for heating?
- geothermal heat pump uses geothermal energy resources to heat buildings
- solar water heaters (by using sun to heat water which is pumped into radiators in the building)
45
What does wind-power involve?
- lots of wind turbines in exposed places like on moors or round coasts
- each turbine has a generator inside and the rotating blades turn the generator and produce electricity
46
What are the advantages of wind power?
- no pollution
- no permanent damage to landscape
- no fuel costs and minimal running costs
47
What are the dis- advantages of wind power?
- initial cost is quite high
- spoil the view
- noisy for people living nearby
48
What are solar cells?
- generate electric current directly from sunlight
- best source of energy to charge batteries in calculators and watches
- often used in remote places
49
What are the disadvantages of solar cells?
- initial cost is high
- generates electricity on a small scale
- cant increase power input when there is extra demand
50
What are the advantages of solar cells?
- no pollution
- sunny countries its very reliable
- after initial cost, the energy is free
51
What is geothermal power?
- possible in volcanic areas or where hot rocks lie quite near the surfaces
- used to generate electricity or to heat buildings directly
52
What are the advantages of geothermal power?
- free energy
- reliable
- little damage to environment
53
What are the disadvantages of geothermal power?
- many suitable locations for power plants
- cost of building a power plant is often high compared to amount of energy it produces
54
What does hydro-electric power require?
- requires flooding of a valley by building a big dam
-
55
What are the advantages of hydroelectric power?
- provide immediate response to increased demand for electricity
- no fuel costs and minimal running costs
- useful way to generate electricity on a small scale in remote areas
56
What are the dis- advantages of hydroelectric power?
- initial cost are high
- big impact on environment due to flooding of the valley
- loss of habitat for some species
57
What is wave power?
- lots of small wave-powered turbines located around the coast
- connected to a generator
58
What are the advantages of wave power?
- no pollution
- after initial cost no fuel costs and minimal running costs
59
What are the dis- advantages of wave power?
- disturbing the sea-bed and the habitats of marine animals
- spoiling the view
- hazard to boats
- initial cost is high
60
What are tidal barriages?
- big dams built across river estuaries with turbines in them
61
How do tidal barrages work?
- as the tide comes in it fills the estuary
- water is then allowed out through the turbines at controlled speed
62
How are tides produced?
- produced by the gravitational pull of the sun and moon
63
What are the advantages of tides?
- no pollution
- reliable (happen twice a day without fail)
- after initial cost, no fuel costs or minimal running costs
64
What are the disadvantages of wave power?
- preventing free access by boats
- spoiling the view
- altering the habitat
65
What are Bio-fuels?
- renewable energy resource created from either plant products or animal dung
- solid, liquid, gas
- burnt to produce electricity
66
What are the advantages of Bio-fuel?
- reliable as crops take short time to grow
- carbon neutral
67
What are the dis-advantages of Bio-fuel?
- cannot respond to immediate energy demands
- cost to refine is very high
68
Why are fossil fuels and nuclear energy reliable?
- enough fossil and nuclear fuels to meet current demand
- extracted from earth at fast enough rate that power plants always have fuel is stock
- running cost is not that expensive
69
What are the disadvantages of fossil fuels and nuclear energy?
- fuels are slowly running out
- if no new resources are found then fossil fuel stock may run out
70
What are the disadvantages of coal, oil and gas?
- release carbon dioxide into the atmosphere when they are burnt
- this CO2 adds to green house effect that contributes to global warming
- also releases sulfur dioxide which causes acid rain (harmful to trees)
71
How can acid rain be reduced?
- taking sulfur out before the fuel is burnt or cleaning up the emissions
72
What does coal mining cause?
- makes a mess of the landscape
- view can be spoilt
73
What do oil spillages cause?
- serious environmental problems
- affecting mammals and birds that live in and around the sea
74
What is the advantages on nuclear power?
- nuclear fuel is cheap but overall cost of nuclear power is high
