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Physics IGCSE * > TOPIC 1 ENERGY > Flashcards

TOPIC 1 ENERGY Flashcards

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1
Q

what are the nine types of energy?

A 
Electrical energy
Light energy 
Sound energy
Kinetic energy
Nuclear energy 
Thermal energy 
Gravitational potential energy 
Elastic potential energy 
Chemical energy j
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2
Q

what is electrical energy (example)

A

it’s energy from when a current flows

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3
Q

what is light energy (example)

A

light bulbs, sun energy

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4
Q

what is sound energy (example)

A

energy from loudspeakers

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5
Q

give an example of kinetic energy

A

anything that moves

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6
Q

give an example of nuclear energy

A

energy released from nuclear reactions

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7
Q

give an example of thermal energy

A

energy that flows from hot objects to colder ones

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8
Q

give an example of GPE

A

possessed by anything which can fall

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9
Q

give an example of elastic potential energy

A

possessed by springs , elastic, rubber bands…

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10
Q

give an example of chemical energy

A

foods, fuels, batteries…

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11
Q

what is energy measure in ?

A

joules (j)

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12
Q

what are the forms of stored energy

A

potential and chemical energy - this type of energy is waiting to be turned into other forms

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13
Q

what is the principle of the conservation of energy?

A

Energy cannot be created or destroyed, only transferred.

+ energy is only useful when it can be transferred from one form to another e.g stored energy

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14
Q

how do you calculate efficiency?

A

(output energy/ input energy) x100

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15
Q

what makes a device insufficient

A

all mechanical devices experience friction - energy is lost as heat

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16
Q

what is work done measure in ?

A

joules (j)

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17
Q

what is the unit of measure for power?

A

Watts (W)

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18
Q

what is energy measured in?

A

joules

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19
Q

what is mass measure in ?

A

kilograms (kg)

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20
Q

what is distance measured in ?

A

metres (m)

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21
Q

what is force measure in ?

A

newtons (N)

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22
Q

what is one measure in?

A

seconds (s)

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23
Q

what is speed measure in ?

A

metres / second

24
Q

what are the units for acceleration

A

metres / seconds squared

25
Q

Define energy

A

Energy is the capacity to do work- measured in joules.

26
Q

Define work done

A

work is when you are moving a subject over a certain distance, with a certain force. This movement is called work.

27
Q

How do you work out work?

A

work done (j) = force (N) x distance (m)

28
Q

what is work done equal to?

A

energy transferred

29
Q

what is gravitational field strength on earth

A

10N

30
Q

how do you work out GPE

A

GPE(N) = mass (kg) x gravitational field strength (10N) x height (m)

31
Q

how do you work out kinetic energy?

A

KE = 1/2 mass x velocity squared

32
Q

what is the relationship between gravitational potential energy and kinetic energy

A

when something falls it’s GPE is converted to KE as the further it falls, the faster it goes - kinetic energy gained = GPE lost.

33
Q

what is power

A

power is the rate of doing work

34
Q

how do you work out power

A

power = work done / time taken

35
Q

what is power measured in ?

A

watts (or joules)

power = how much energy per second, so, watts = joules per second

36
Q

what are the main features of a power stations (fossil fuels)

A

generators of electricity, boilers, turbines and condensers

37
Q

what are the problems with fossil fuel power stations

A

global warming and air pollution

38
Q

calculation of average power

A

P=Fv

power = force x velocity

39
Q

How do you calculate breaking distance (m)

A

Breaking distance (m) = Kinetic energy (j) / force (N)

40
Q

How do you calculate height ?

A

height = KE / (mass x gravity)

41
Q

how do you work out time?

A

time = energy / power

42
Q

how do you work out energy transferred ?

A

energy = power x time

43
Q

what is conduction ?

A

conduction of heat is the process where vibrating particles pass on their extra kinetic energy to neighbouring particles - conduction of heat mainly happens in solids

44
Q

why is conduction best in metals

A

it’s best in metals as they have free electrons

45
Q

what is convection

A

convection occurs when the more energetic particles move from the hotter region to the cooler region and take their heat energy with them - the circulation of a fluid by heating.

46
Q

what is radiation

A

thermal or infrared radiation involves the emission of electromagnetic waves of a certain range of frequencies. It’s next to the visible light of the electromagnetic spectrum. All objects constantly emit and absorb heat energy.

47
Q

how does conduction work?

A

Atoms vibrate and pass on the vibrations to the nearest atom by colliding and ‘shaking’ them- because of this conduction take place best in solids where particles are closer together.

48
Q

How does convection occur ?

A

Heating a fluid makes it less dense and therefore the hot fluid rises. When it rises, it starts to cool and falls back down to the heat source causing a convection current. This circulation continues until the fluid is an equilibrium.

49
Q

what objects emit infrared radiation?

A

all objects that are above absolute zero (-273C or 0K) emit infrared radiation.

hotter objects emit more

50
Q

how does infrared energy travel

A

travels in electromagnetic waves and which is why it can travel in a vacuum as it does not need particles to be transferred

51
Q

what objects reflect infrared radiation

A

light coloured, shiny, smooth objects

52
Q

what objects absorb infrared radiation the best

A

dark coloured, rough/ matt surfaces

53
Q

what role does convection take place in everyday phenomena

A

costal wind is caused by convection currents. Air above land warms up quicker than the air above the sea. The air above the land rises and moves towards the sea, cools and moves back towards the land causing an inward wind. This cycle is reversed at night.

54
Q

how is insulation used in buildings

A

insulation is used to stop heat transfers

examples:
double glazed windows- the two layers of glass with a narrow air gap in between which reduces conduction and convection

cavity wall insulation- the foam in between the bricks stop convection currents being set up in the gap and radiation across the gap. the insulating foam contain small air pockets which reduce heat loss by conduction and convection

55
Q

how is insulation used to reduce heat transfer in the human body

A

1) when your body is cold your hairs on your skin stand up and trap a thicker layer of insulating air around the body. this limits heat loss by convection
2) humans have layers of fat under their skin to insulate their body
3) layers of clothes reduce heat transfer- the pockets of air trapped in the clothes and between layers mainly reduce heat transfer by conduction and convection- they also reduce heat loss from your body by radiation as some materials absorb heat radiated out by our bodies.

Physics IGCSE * (3 decks)

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