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Flashcards in Energy Resources And Energy Transfer Deck (59)
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0
Q

Define the term energy

A

Energy is the ability to do work.

1
Q

Define thermal energy

A

The energy possessed by hot objects, caused by the random motions of the particles in them

2
Q

Define light energy

A

The energy emitted by luminous objects

3
Q

Define electrical energy

A

The energy carried around electrical circuits by charged particles

4
Q

Define sound energy

A

The energy carried by longitudinal waves from vibrating objects

5
Q

Define kinetic energy

A

The energy possessed by any moving object.

6
Q

Define chemical energy

A

The energy contained in the bonds between atoms, which can be released in chemical reactions

7
Q

Define nuclear energy

A

The energy contained inside atomic nuclei, which can be released by certain nuclear processes (radioactive decay, fission and fusion)

8
Q

Define elastic potential energy

A

The energy to stretch or squashed object possesses

9
Q

Define gravitational potential energy

A

The energy that an object possesses by virtue of having been lifted up in a gravitational field.

10
Q

What energy transfer is happening at a coal fire power station?

A

Chemical energy into thermal energy which is used to boil water to produce hot, high-pressure steam, which has elastic potential energy. The steam then drives a turbine, producing kinetic energy. The tubing in turn drives a generator producing electrical energy.

11
Q

How do you walk out the value of energy of a pendulum?

A

Assuming there is no friction or air resistance, is it equal to both the KE and GPE values at any point added together at they should be opposite.

12
Q

What is the GPE of a bungee jumper like on a graph?

A

A straight line diagonally going down from right to left as his GPE falls proportionally.

13
Q

What is the KE of a bungee jumper like?

A

It increases as he falls but then he he begins to slow down as the bungee becomes stretch so the graph reaches a point and decreases.

14
Q

What is the EPE of a bungee jumper like on a graph?

A

It has nothing for a while as he’s falling but then it becomes a curved line up.

16
Q

How do you work out efficiency?

A

Efficiency=useful energy output/total energy input

x100 for a percentage.

16
Q

Name 4 ways to lose energy:

A

Friction between moving parts.
Resistance of wire causes the wire to get hot when current passes through.
Air resistance causes energy transfer to surroundings.
Sound created by machinery.

17
Q

What is the only thing that is 100% efficient and why?

A

A heater because every appliance loses some useful energy as heat e.g a lamp will only use a percentage of its total energy on light energy. A high proportion will be lost as heat. Only a heater can be totally efficient as it can’t lose energy to heat.

18
Q

Solution for losing energy due to sound created by machinery.

A

Boil the parts, change the materials, reduce the number of parts, tighten things up.

19
Q

How to reduce loss of energy due to air resistance causing energy transfer to surroundings.

A

Streamlined shaped objects.

20
Q

How to reduce loss of energy when the resistance of wire causes the wire to get hot when current passes through.

A

Changing the material to low resistance objects.

21
Q

LEARN HOW TO DRAW S(K)ANKEY DIAGRAMS

A

Okeh

22
Q

What is the principle of conservation of energy and why is it important?

A

It means energy can neither be created nor destroyed, it can only be transformed from one state to another. this means that in any process of energy transfer the total amount of energy stays the same.

24
Q

If you drop a book on the floor you may think that some of the energy has disappeared, why has it really gone?

A

A small amount will have been transferred into thermal energy.

24
Q

What is geothermal energy?

A

Naturally occurring Energy produced by the heat of the earth’s core. This energy is accessible in places where volcanic activity is frequent.

26
Q

What is geothermal energy?

A

Naturally occurring heat energy from subterranean rocks is used to boil water. The steam turns turbines that drive generators. Long life span, mostly underground, relatively quiet, no greenhouse gases. High upfront cost, need high water supply, only can be used in certain places.

27
Q

What is nuclear energy?

A

Controlled nuclear fission reaction produces heat to boil water, the steam turns turbines that drives generators. Lots of energy from a little space, no GHG. Non-renewable (uses finite resources), produces radio-active waste, risks a nuclear disaster

28
Q

What are fossil fuels?

A

Fossil fuels include oil, gas and coal. These are burnt to boil water and the steam turns the turbines that drive the generators. They are easily transportable and a single station can generate large amounts of energy. These are non-renewable, finite resources and produce greenhouse gases like CO2 and other polluting gases e.g. SO2

28
Q

What are hydroelectric power stations?

A

Water stored behind a dam flows out through turbines that drive generators converting the GPE and KE of water into electrical energy. Renewable, no polluting gases produced, can be started up quickly in times of need. Only feasible in mountainous areas, or on large rivers and flooding behind dams can cause environmental problems

29
Q

What is hydroelectric power?

A

Water stored behind a dam flows out through turbines that drive generators converting the GPE and KE of water into electrical energy. Renewable, no polluting gases produced, can be started up quickly in times of need. Only feasible in mountainous areas, or on large rivers and flooding behind dams can cause environmental problems

31
Q

What is tidal power?

A

Barriers across tidal estuaries can harness the kinetic energy of the sea, which drives water turbines as the tide comes in. Renewable, tides are reliable, produces much more energy than air as water is so much denser, only cost is to initial equipment. Expensive to build, can only be built on coastlines

32
Q

What is wind power?

A

Wind driven generators have been built to convert the wind’s kinetic energy into electrical energy. It is a renewable, tried and tested technology, remote areas can use wind. Spoil the look of the countryside, expensive to build, can only use in windy areas.

33
Q

What is solar power using solar cells (solar active)?

A

Photovoltaic cells convert light energy from the sun into electrical energy. Renewable, silent, proven technology. Currently expensive and not very efficient, large collecting area needed - potential visual pollution

34
Q

Advantages and disadvantages of different energy resources.

A
Cost
Renewable/non-renewable
Greenhouse gas emissions 
Supply and demand 
Environmental impact
Location
35
Q

What do you have to consider about cost when comparing advantages and disadvantages?

A

The cost of installing power stations and generating electricity. With nuclear power stations, decommissioning a reactor is very costly.

35
Q

What do you have to consider about greenhouse gas emissions when comparing advantages and disadvantages?

A

Burning fossil fuels produces CO2, which is a greenhouse gas. They trap heat in our atmosphere and contribute to global warming

36
Q

What do you have to consider about renewable/non-renewable when comparing advantages and disadvantages?

A

Fossil fuels are a finite source, this means in the future other alternative MUST be found (why not do it as soon as possible?).

37
Q

What do you have to consider about supply and demand when comparing advantages and disadvantages?

A

The demand on electricity varies over a period of 24 hours and longer. Nuclear power stations cannot be turned on and off quickly and therefore cannot respond to demand surges. Some renewables, e.g wind and tidal power, do not produce energy all the time.

38
Q

What do you have to consider about location when comparing advantages and disadvantages?

A

It makes sense to build power stations close to centres of demand like urban and industrial areas because energy will be wasted in transmission. Tidal, wind, geothermal and hydroelectric energy sources are limited to suitable geographical locations and these are often far away from centres of demand.

40
Q

What do you have to consider about location when comparing advantages and disadvantages?

A

It makes sense to build power stations close to centres of demand like urban and industrial areas because energy will be wasted in transmission. Tidal, wind, geothermal and hydroelectric energy sources are limited to suitable geographical locations and these are often far away from centres of demand.

41
Q

What is wave energy?

A

Waves drive generators by a bobbing motion. Reliable as waves are constant, no GHG, produces lots of energy. Power farms are ugly, high level of maintenance, expensive to build, could negatively affect sealife

42
Q

What is solar power using solar heating (solar passive)?

A

Sunlight is turned directly into thermal energy via solar panels. Renewable, tried and tested, silent. Large collecting area needed, works best in sunny areas, just produces heat not electricity

43
Q

What is the equation for work done?

A

Work done = force x distance moved in the direction of the force

44
Q

Why is work done equal to the energy transferred?

A

When work is done, the energy expended must go somewhere: it could end up being stored as gravitational potential energy if an object is lifted, as kinetic energy if an object is accelerated etc - or as heat if the object is decelerated or if work is done against a frictional force.
In each case, because of the Principle of Conservation of Energy, the work one is equal to the energy transferred.

45
Q

What is the equation for gravitational potential energy?

A

gravitational potential energy = mass x g x height

GPE = mgh

46
Q

What is the equation for kinetic energy?

A

kinetic energy = 1/2 x mass x speed2

KE = 1/2mv2

47
Q

How does conservation of energy produce a link between GPE, KE and work?

A

In some ‘mechanical systems’ there is an interchange between GPE and KE (or vice versa).
For example, when an object is launched upwards, KE turns into GPE and when it falls down again GPE turns into KE. If we assume that no energy is lost during this process, then the expressions for GPE can be equated to work various things out as in these scenarios we can say that:
1/2mv2 = mgh

48
Q

What is power?

A

The rate of transfer of energy or the rate of doing work

49
Q

What is the relationship between power, work done (energy transferred) and time taken?

A
power = work done / time taken
P = W / t
50
Q

Watt is the unit of power?

A

Watts

51
Q

How can energy transfer take place?

A

Thermal radiation - the transfer of heat energy by electromagnetic waves
Conduction - the transfer of heat energy by particles (mainly in solids
Convection - the transfer of heat energy by particles (mainly in liquids and gases)

52
Q

Explain radiation

A

Heat radiation can also be called infrared radiation and it consists purely of infrared waves.
1) All objects are continually emitting and absorbing heat radiation
2) An object that’s hotter than its surroundings emits more radiation than it absorbs (as it cools down).
An object that’s colder than its surroundings absorbs more radiation than it emits (as it warms up)
3) You can feel this heat radiation

53
Q

Explain conduction

A

Conduction of heat is the process where vibrating particles pass on their extra kinetic (or heat) energy to neighbouring particles.
In a solid, the particles are held tightly together. So when one particles vibrates it collides with other particles nearby and the vibrations quickly pass from particle to particle.
This process continues through the solid and gradually some of the extra kinetic energy (or heat) is passed all the way through the solid, causing a rise in temperature at the other side of the solid. And therefore an increase in the heat radiation from its surface.

54
Q

What effect does temperature difference have on heat transfers?

A

The bigger the temperature difference, the faster heat is transferred.

55
Q

Why can’t convection happen in solids?

A

Because the particles can’t move about, only vibrate

56
Q

Explain convection using the example of the immersion heater (used in kettles and hot water tanks)

A

1) Heat energy is transferred from the heater coils to the water by conduction (particle collisions)
2) The particles near the coils get more energy, so they start moving around faster
3) This means that there’s more distance between them i.e. the water expands and becomes less dense
4) This reduction in density means the hotter water will rise above the denser, cooler water
5) As the hot water rises it displaces the colder water out of the way making it sink towards the heater coils
6) This cold water is then heated by the coils and rises etc. You end up with convection currents going up, round and down, circulating the heat energy through the water

57
Q

What is an example of convection used in the home?

A

Radiator, same as immersion heater, just with air.
Radiator heats the air, this air is less dense so rises and displaces cooler air, cool dense air falls, cooler air flows to fill the gap left by the rising heated air and moves towards the radiator.

58
Q

What are ways of insulating houses to reduce heat transfer?

A

1) loft insulation - a thick layer of fibreglass wool laid out across the loft floor and ceiling reduces heat loss from the house by conduction and convection
2) double glazing - two layers of glass with a narrow air gap between reduce conduction and convection as air is a bad conductor and it is also a barrier
3) thick curtains - reduces heat loss by conduction and radiation
4) cavity wall insulation - foam squirted into the gap between the bricks stops convection currents being set up in the gap and radiation across the gap. The insulating foam and the air pockets trapped in it also helps reduce heat loss by conduction as air is a bad conductor
5) draught proofing - strips of foam and plastic around doors and windows stop draughts of cold air blowing in, reducing heat loss by convection

59
Q

What are ways that humans reduce heat transfer from their bodies?

A

1) In the cold, hair erector muscles cause hair on the body to rise to trap a thicker layer of insulating air around the body - this limits the amount of heat loss by convection, conduction and radiation
2) Humans wear layers of clothes to reduce heat transfer - the pockets of air trapped in the clothes between layers mainly reduce heat transfer by conduction and convection
3) Clothes also reduce heat loss by radiation from the body, as the material absorbs some heat radiated out by our bodies