Energy Flashcards

1
Q

State the nine different forms of energy

A

Kinetic (Ke) - movement energy

Gravitational Potential Energy (gpe) - when an object is lifted

Elastic Potential Energy (epe) - when an object is stretched or compressed

Chemical - stored in chemical bonds (fuels like food)

Heat (thermal) - often wasted energy

Sound - often wasted energy

Light - often wasted energy

Electrical

Nuclear- stored in nuclear bonds and released in atomic bombs/nuclear power stations (from the nucleus of an atom)

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2
Q

What is an easy way of remebring the nine forms of energy?

A

Every (elastic)

Kid (kinetic)

Loves (light)

Not (nuclear)

Hates (heat)

G (gravitational)

C (chemical)

S (sound)

E (elastic)

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3
Q

State the law of the conservation of energy

A

‘Energy cannot be created or detroyed but can be converted from one form into another.’

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4
Q

Can the amount of energy in the universe change? Why?

A

no because of the principle of the conservation of energy (it cannot be created or destroyed so there cannot be more or less)

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5
Q

What is energy?

A

energy is the ability to do work on objects and it converts from one form to another

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6
Q

What is work?

A

work is done when force is applied to an object and the object is moved through a distance

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7
Q

What is the equation for work?

A

work = force x distance moved in the direction of the force

measurements - Joules (J) = Newtons (N) x Metres (m)

w= f x d

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8
Q

What is the equation for GPE?

A

GPE= mass x gravity x height

measurments- Joules (J) = kg x N/kg x m

gpe = mgh

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9
Q

What is the equation for kinetic energy?

A

kinetic energy= 1/2 x mass x velocity2

measuremnts - Joules (J) = kg x v in m/s

Ek = 1/2 mv2 (notice only v is squared)

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10
Q

What is power?

A

power is the rate of doing work

rate means per time/per unit time

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11
Q

What is the equation for power?

A

power = work ÷ time

p= w÷t

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12
Q

What is power measured in?

A

power is measured in Watts

1W= 1 J/s

1KW = 1000W

1MW = 1000,000 W

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13
Q

A 65kg girl enters receptipn at A floor.She walks down to G floor and then all the way up to D floor. All the floors are 6m high. Calculate the increase in GPE for the girl in going between G and A floor

A

GPE= mgh

=65 x 10 x(6 x 1)

=3900 J

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14
Q

A 65kg girl enters receptipn at A floor.She walks down to G floor and then all the way up to D floor. All the floors are 6m high. Calculate the total increase in her GPE from G to D floor

A

GPE= mgh

= 65 x 10 x (6 x 4)

= 15600J

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15
Q

A 65kg girl enters receptipn at A floor.She walks down to G floor and then all the way up to D floor. All the floors are 6m high. Explain why she feels tired

A

she has done work by walking

she has converted chemical energy into gravitational, kinetic and thermal energy

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16
Q

A 200g mass is lifted 5.0m off the ground. Calculate the work done in lifting it

A

GPE= mgh

0.2 (remember to convert 200g into kg) x 10 x 5

=10J

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17
Q

A 900kg car is moving at 5 m.s. how much kinetic energy does it have?

A

Ek= 1/2 mv2

=1/2 x 900 x (5)2

=450x25

=11250 J

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18
Q

A 90kg runner is moving at a constant velocity of 12 m/s. Calculate the kinetic energy

A

Ek= 1/2 x 90 x (12)2

=6480J

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19
Q

A 1000kg car is travelling at 15m/s on the motorway. Calculate the work done (change in energy) when it accelerates to 18 m/s

A

Ek= 1/2 x 1000 x (182-152) [You have to take the original velocity away from the new velocity]

= 49500J

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20
Q

Rearrange the kinetic energy equation so that velocity is the subject

A

Ek=1/2 x m x v2

Ek x 2 = m x v2

Ek x 2 ÷ m = v2

v2 = 2Ek/m

v = √ 2Ek/m

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21
Q

A 700kg car has 12000J of kinetic energy. Calculate its velocity

A

v = √ 2Ek/m

v = √ 2x12000/700

=5.86 m/s (2.dp)

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22
Q

What is the efficiency and its equation?

A

how much useful energy is produced from the total energy put into the machine

effeciency = total useful output/total input x 100

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23
Q

What is a sankey diagram?

A

it shows how well a machine uses energy

shows efficiency or inefficiency of something

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24
Q

How do you draw a Sankey Diagram?

A

the thicker the arrow, the more energy it represents

useful energy is shown going left or right

wasted energy is shown going upwards or downwards

the length of the arrows doesn’t matter

if on graph paper or specified, every square and placing matters (the starting of the output and the calculations of the thickness of the arrow)

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25
A car increases its kinetic energy from 120,000J to 150,000J in 15 seconds. What work is done by the car in increasing its kinetic energy?
30,000J
26
A car increases its kinetic energy from 120,000J to 150,000J in 15 seconds. What is the power output of the car?
=30,000J ÷ 15 secs =2,000W (2KW)
27
A car increases itsr kinetic energy from 120,000J to 150,000J in 15 seconds. The engine is rated at 3.5KW. How efficient it it?
efficiency =output/input x 100 =(30,000/15) / 3500 x 100 =2000/3500 x 100 =57%
28
When a ball is held above the ground what form of energy does it have?
gravitational potential energy (gpe)
29
What form of energy does a falling ball have half way to the ground?
1/2 gpe 1/2 kinetic energy
30
What form of energy does a ball have as it is bouncing?
elastic potential energy (epe) heat (thermal) energy sound energy
31
What happens in terms of energy as a ball falls?
gpe is converted into kinetic energy
32
What happens in terms of energy as a ball is during the bounce stage?
kinetic energy is converted into elastic potential energy, thermal energy and sound energy
33
What happens in terms of energy as a ball bounces up to its highest point?
elastic potential energy is converted into kinetic energy which is converted into gravitational potential energy
34
A scientist observes an experiment of a falling apple. He notices that the actual velocity of the apple is much lower than the value calculated. Explain what could cause this observation
he didn't take into consideration air resistance air resistance will do work on the apple as it falls converting (or transferring) some of the oringinal gpe into thermal energy and sound energy
35
An observer says that the man must be cheating because he starts off at 4m and ends up 6m off the ground. He says that he is breaking the law of the conservation of energy. He also says that after reach 6m of the ground (at D) he landed and only reached the top of the half pipe at the other side (at A). He then says that he must of cheated as he should have reached 6m off the ground at the other side too. Evaluate this comment
(do not need to mention all of these) mention of 3000J of energy at the start needs more energy to reach D extra 1500J needed skateboarder must add extra 1500J skateboarder does 1500J of the work w=fd (by the skateboarder) mention that energy must be conserved mention of friction mention dissipated energy into the atmosphere mention would need to push/do workto reach C to overcome friction/ air resistance not cheating (if liknked to scientific reason)
36
What is the difference between renewable and non-renewable fuels?
renewable = replenishes itself so will never run out non-renewable = used faster than made so will one day run out
37
Give some examples for renewable and non-renewable fuels?
renewable = solar, tidal, wave, wind, hydrolic, wood, geothermal non-renewable = oil, coal, natural gas, nuclear
38
What are the names of fossil fuels?
coal, oil, natural gas (non-renewable)
39
What is the greenhouse effect?
caused by greenhouses gases (CO2 methane) and cause global waming 1. absorbed radiation - the Earth absorbs radiation from the sun 2. Reflected radiation - greenhouse gases absorb some outgoing radiation 3. Greenhouse gases - greenhouse gases emit absorbed raidation - this warms the earth and its atmosphere
40
What are some disadvantages of burning fossil fuels to generate electricity?
All fossil fuels release carbon dioxide (CO2) into the atmosphere when burned in power stations. All this CO2 contributes to global warming and climate change Burning coal and oil also releases sulphur dioxide (SO2), which causes acid rain. Acid rain can harm trees and soils and can have a huge impact on wildlife and the environment They will eventually run out
41
What is meant by 'clean' fuel?
doesn'thurt the planet, global warming they don't produce pollution or greenhouse gases
42
What are the advantages of using non-renewable energy sources??
Burning folssil fuels releases a lot of energy, relatively cheapily Energy from fossil fuels doesn't rely on weather, like a lot of renewable energy, so it's a reliable energy source We have lots of fossil fuel power stations already, so we don't need to spend money on new technology to use them
43
What are the disadvantages of using Solar Power, Wind Power, Tidal Power, Wave Power, Geothermal, Wood to generate electricity?
wood takes a lot of space geothermic is expensive in the UK not constant or necassarily quick effects wildlife and areas such as flooding and birds
44
Why is geothermal energy expensive and not a good source of energy in the UK?
you would have to dig down very deep which is very expensive and time consuming and you would only produce a small amount of energy
45
Why is solar powerful ineffective in the UK?
there is not enough sunlight to generate enough power
46
Talk about the fact that some power stations respond quickly to changes in demand?
power stations = slow hydroelectric power = fast responses differ
47
Why are nuclear power stations expensive to decommision?
you have to dispose of the waste they only last 30 years nuclear waste must be disposed off carefully land has to be un-radioactive after burning coal takes a while
48
What are the cost considerations in the choice of power stations?
different expenses depening on size - they have differnet energy outlets decommisioning and removing nuclear waste is very expensive
49
Why does demand for electricity change through the day and seasons?
winter needs more electricity - heat especially sleeping = less electricity celebrations or events e.g. the world cup
50
What causes predictable changes in demand on a day to day and season to season basis?
rush hour morning kettle sleep vs daytime tv
51
what is the energy transfer for an electric kettle boiling water
electrical energy to thermal energy
52
what is the energy transfer for coal burning in an open fire
chemical energy to light energy
53
what is the energy transfer for a weight as it is falling through the air
kinetic energy to gravitational potential energy
54
it's a typical english winter everning; dark, wet but calm the demand for electricity is also typical for this time of year and is being met by all fossil fuel power stations working at maximum output along with half the nuclear power stations an event occurs that suddenly causes demand throughout the UK to increase by 50% use your knowledge of start up times and reliability of energy sources to say whether or not you would use these energy resources and why: the remaining nuclear power stations wind farms across the country solar power across the country hydroelectric plants in Scotland
the remaining nuclear power stations: no - slow start up, couldn't use staright away wind farms across the country: no - the weather is calm (no wind) solar power across the country: no - it is dark (nighttime) so there is no sun hydroelectric plants in Scotland: yes - very quick and reliable, it is a wet day meaning it rained all day
55
less time = ... work = ... powerful
less time = **less** work = **less** powerful
56
A light bulb changes **...** energy into useful **...** energy
A light bulb changes **electric** energy into useful **light** energy
57
A petrol engine changes **...** energy into useful **...** energy
A petrol engine changes **chemical** energy into useful **kinetic** energy
58
Most of the energy lost is as **...** energy
Most of the energy lost is as **thermal** energy
59
A human muscle changes **...** into useful **...** energy
A human muscle changes **chemical** into useful **kinetic** energy
60
convert 1kJ into J
1kJ = 1000J
61
Which energy source only works in volcanic regions?
geothermal
62
Which energy source is usually situated on a hill?
wind
63
Which fuel produces the most sulphur dioxide, a greenhouse gas?
coal
64
A microphone changes **...** into useful **...** energy
A microphone changes **sound** into useful **electric**​ energy
65
What happens to wasted energy?
wasted energy is dissipated into the suroundings
66
Energy is **...**
Energy is **the ability to do work**
67
What are two examples of light energy?
the Sun light bulbs
68
What is an example of sound energy?
loudspeakers
69
What are three examples of elastic potential energy?
springs elastic rubber bands
70
What are three examples of chemical energy?
foods fuels batteries
71
Energy is only useful when **...**
Energy is only useful when **it is transferred from one form to another**
72
A television turns **...** energy into **...** and **...** energy
A television turns **electrical** energy into **light** and **sound** energy
73
Toy car batteries turn **...** energy into **...** energy into **...** , **...** , **...** and **...** energy
Toy car batteries turn **chemical** energy into **electrical** energy into **kinetic** , **heat** , **sound** and **light** energy
74
Battery chargers convert **...** energy into **...** energy
Battery chargers convert **electrical** energy into **chemical**energy
75
Electrical devices convert **...** energy into **...** , **...** and **...** energy
Electrical devices convert **electrical** energy into **sound** , **light** and **heat** energy
76
Batteries convert **...** energy into **...** energy to run electrical devices
Batteries convert **chemical** energy into **electrical** energy to run electrical devices
77
Gravitation and elastic potential energy always get converted into **...** energy first
Gravitation and elastic potential energy always get converted into **kinetic** energy first
78
A crane converts **...** energy into **...** energy into **...** energy
A crane converts **chemical** energy into **kinetic** energy into **gravitational potential** energy
79
A falling object converts **...** energy into **...** energy
A falling object converts **gravitational potential** energy into **kinetic** energy
80
An archer converts **...** energy into **...** energy
An archer/bow converts **chemical** energy into **elastic potential** energy
81
A bow/arrow converts **...** energy into **...** energy
A bow/arrow converts **elastic potential** energy into **kinetic** energy
82
A powerful machine is one which **...**
A powerful machine is one which **transfers a lot of energy in a short space of time**
83
What are the unites of work?
Joules (J)
84
What are the units of energy?
Joules (J)
85
What are the units of power?
Watts (W)
86
What does a detailed sanky diagram look like (i.e. one on a graph)?
87
From where is most of our energy provided?
fossil fuels (non-renewable energy resources)
88
What is energy conservation?
using fewer resources because of the damage they do and because they might run out
89
Most power stations use **...** to drive a turnbine. How does this work?
chemical energy, in the form of fuel, is fed into a boiler Heat energy released is used to heat water to create steam which turns a turbine (kinetic energy) The kinetic energy turns the generator which converts the kinetic energy into electrical energy which flows to a grid chemical energy → heat energy → kinetic energy → electrical energy
90
How does a nuclear reactor work?
nuclear fission, e.g. of uranium, priduces heat to make steam to drink turbines, rather than burning nuclear energy → heat energy → kinetic energy → electrical energy
91
Nuclear reactors are **cheap/expensive** to build and mantain They take a **shorter/longer** time to start up than fossil fuel ones
Nuclear reactors are **expensive** to build and mantain They take a **longer** time to start up than fossil fuel ones
92
What are the environmental impacts of using a nuclear reactor?
processing uranium before you use it causes pollution there is always a risk of leaks of radioactive material, or even a major catastrophe like at Chernobyl you always get radioactive waste
93
What are the advantages to nuclear power?
it doesn't produce any of the greenhouse hases which contribute to global warming there's still plenty of uranium left in the ground (although it can take a lot of money and energy to make it suitable for use in a reactor)
94
How do wind turnbines work?
Wind power involves putting lots of wind turbines up in exposed places - like on moors, around the coast or out at sea Wind turbines convert kinetic energy of moving air into electrical enrgy. Wind turns the bldes, which turn the generator inside it
95
What are the advantages to wind turbines?
they are quite cheap to run - they're very tough and reliable and the wind is free wind power doesn't produce any polluting waste it is renewable - wind is never going to run out
96
What are the disadvantages to wind turbines?
they spoil the view you need 1500 wind turbines to replace one coal-fired power station and 1500 of them cover a lot of ground which has a big effect on the scenery - annoying for the people who live nearby sometimes the wind isn't strong enough to generate any power it is impossible to increase power supply when there's extra demand although the wind is free, its expensive to set up a wind farm, especially out at seas
97
Where is geothermal energy possib;e? What is the source of much of the heat?
geothermal energy is only possible in certain places where hot rocks lie quite near to the surface the source of much of the heat is the slow decay of various radioactive elements. including uranium deep inside the Earth
98
How does geothermal energy work?
water is pumped in pipes down to the hot rocks and forced back up due to pressure to turn a turbine which drives a generaor heat energy → kinetic energy → electrical energy in some places, geothermal energy is used to heat building directly
99
What is are the advantages of geothermal energy?
it is free it is a renewable energy resource there are no real environmental problems
100
What is are the disadvantages of geothermal energy?
the cost of driviling down several kilometres the cost of building a power plant is often high compares to the amount of energy we can get out of it there are few places where geothermal energy seems to be an economic option
101
What do solar cells do?
solar cells (photocells) transform light energy from the Sun directly into electrical energy they generate direct current (d.c.) - the same as a battery
102
What are the advantages of solar cells?
the Sun provides a renewable energy source - it won't run out (not for 5 billion years) solar cells are expensive initially, but after that the energy is free and the running costas are almost nil there's no pollution (although they use a fair bit of energy to manufacture in the first place)
103
When are solar cells used?
solar cells are used to generate electricity on a relatively small scale, e.g. powering individual homes they are the best way to power calculators or watches that don't use much energy
104
Where are solar cells used?
solar cells are used in remote places where there's not much choice (e.g. deserts) and in satellites
105
Are solar cells connected to the National Grid? Why?
It's often not practical or too expensive to connect solar cells to the National Grid - the cost of connectng them can be enormous compared with the value of electricity generated
106
When do solar cells generate electricity? What can be done to store energy?
solar cells can only generate enough electricity to be useful if they have enough sunlight - which can be a problem at night (and in the winter in some places) the cells can be ilnked to rechargeable batteries to create a system that can store energy during the day for use at night
107
What are solar panels? How do they work?
solar panels are more simple than solar cells - they're basically just black water pipes inside a glass box the glass lets heat and light from the Sun in, which is then absorbed by the black pipes and heats up the water
108
What are the advantages and disadvantages of solar panels? When are they used?
they cost money to set up, but are renewable and free after that they're only used for small-scale energy production
109
How does wave power work?
one way of harvesting wave power is with lots of small wave converters located around the coast as waves come in to the shore they provide and up and down motion which can be used to drive a generator the kinetic energy of the waves is converted into electrical energy
110
What are the advantages of wave power?
there is no pollution it is renewable the initial costs are high but there are no duel costs and minimal running costs
111
What are the disadvantages of wave power?
wave converters spoil the view wave converters are hazards to boats it is fairly unreliable, since waves tend to die out when the wind drops
112
On what scale is wave energy used?
wave energy is unlikely to provide energy on a large scale but it can be very useful on small islands
113
What are tidal barrages and how do they work?
tidal barrages are big dams built across river estuaries with turbines in them as the time comes in it fills up the estuary to a height of several metres this water can then be allowed out through turbines at a controlled speed it also drives the turbine on the way the kinetic energy of the water is converted into electrical energy by the turbines and a generator
114
What are the advantages to tidal power?
there is no pollution it's renewable tides are pretty reliable, but the height of the tide is variable so lower tides will provide less energy than higher ones initial costs are moderately high, but there's no fuel costs and minimal running costs
115
What are the disadvantages to tidal power?
tidal barrages prevent free access by boats tidal barrages spoil the view tidal barrages alter the habitat of the wildlife
116
How does hydroelectric power work?
hydroelectric power often requires the flooding of a valley by building a dam rainwater is caught and allowed out through turbines, converting the gravitational potential energy of the water into kinetic energy as it falls, which is then converted into electrical energy by the generator gravitational potential energy → kinetic energy → electrical energy
117
What are the advantages to hydroelectric power?
it's a renewable resource it can respond immediately to increase demand - if more energy is needed than the National Grid can supply, the water is released there is no problem of reliability except in times of drought initial costs are high, but there's no fuel and low running costs
118
What are the disadvantages to hydroelectric power?
There is no pollution (as such), but there's a big impact on the environment due to flooding the valley (rotting vegetation releases methane and CO2) and possible loss of haitat for some species - location in remote valleys can avoid some of these problems The reservoirs can also look very unsightly when they dry up - location in remote valleys can avoid some of these problems
119
**Pumped storage gives extra supply just when it's needed** Why is is it needed? How does this work?
Most large power station have huge boilers which have to be kept running all night even though demand is very low. This means a surplus of electricity at night - and its very difficult to find a way to strore this spare energy of electricity at night. Pumped strogae is one of the best solutions In pumped storage, 'spare' night-time electricity is used to pump water up to a higher reservoir This can then be released quickly during periods of peak demand such as at teatime each evening, to supplement the steady delivery from the bigger power stations It is simply a way of storing energy which has already been generated