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GCSE Physics <3 > Topic 1 – Energy fundamentals > Flashcards

Topic 1 – Energy fundamentals Flashcards

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1
Q

what is kinetic energy

how much kinetic energy does a stationary object have?

A

energy stored in moving objects

none

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2
Q

whats the equation for kinetic energy

A

kinetic energy = 0.5 x mass x speed^2

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3
Q

what is elastic potential energy

A

when we stretch a spring were applying a force to change its length (doing work) we are putting in energy to stretch the spring, the stored energy is elastic potential energy

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4
Q

whats the equation for elastic potential energy (g)

A

elastic potential energy = 0.5 x spring constant x extension^2

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5
Q

what happens to a graph if you overstretch a spring

A

graph won’t be directly proportional as springs been stretched beyond limit of proportionality

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6
Q

extension must always be in:

A

metres

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7
Q

what is gravitational potential energy

A

the energy stored in an object due to its position above the earths surface

this is due to gravity acting on an object

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8
Q

how to calculate gravitational potential energy

A

gpe = mass x grav field strength x height

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9
Q

whats thermal energy

A

the energy stored due to an objects temperature

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10
Q

whats the law of conservation of energy

A

energy can be transferred usefully, stored or dissipated but it cannot be created or destroyed

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11
Q

whats a system

A

an object or group of objects

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12
Q

in a CLOSED system energy_____

A

cannot enter or leave

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13
Q

what are the energy transfers in a pendulum?

A

mass has maximum GPE, then its transferred to KE , then mass has maximum KE at bottom (mid swing) then its transferred back to GPE where it has max GPE one more

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14
Q

whats an issue with the pendulum example?

A

does not consider friction

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15
Q

what does friction cause (in terms of energy transfer)

A

causes energy to be transferred to thermal energy

energy has been dissipated as thermal energy is less useful

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16
Q

where is friction on the pendulum?

A

friction on the fixed point

friction as the pendulum pass through the air particles

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17
Q

what does friction cause the pendulum to do

A

gradually swing with less energy and eventually stop

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18
Q

how can we reduce unwanted energy transfers in a pendulum

A

remove friction by:

using a lubricant on fixed point

removing air particles from around pendulum

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19
Q

what are the energy changes in a bungee jumper

A

GPE at start,,, energy is transferred to KE as man falls.
KE store is at it max when rope JUST starts to tighten, KE store of fully extended rope is 0 (JUMPERS NOT MOVING)
all energy is transferred to elastic potential energy
ElP —> KE as rope coils
KE—-> GPE during ascent
at top, all is GPE

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20
Q

why will bungee jumper never return back to his original position?

A

energy is dissipated as thermal energy

(friction w air particles & stretching effects of bungee rope which arent fully elastic)

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21
Q

what is work done

A

when energy is transferred from one store to another

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22
Q

what does mechanical work involve

A

using a force to move an object

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23
Q

whats electrical work

A

a current transferring energy

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24
Q

whats the equation for work done?

A

work done (J) = force x distance (m)

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25
Q

what is power

A

the rate at which energy is transferred or at which work is done

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26
Q

what are the equations for power (W)

A

energy transferred (J) / time (s)

or

work done (J) / time (s)

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27
Q

1 watt is the same as____

A

1 J per second

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28
Q

whats the equation for effienciency

A

useful energy output / total energy output

or

useful power output/ total power INPUT

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29
Q

whys kettle more effiecnt then heating water in pan

A

the heating element is inside so less thermal energy lost to the environment

made of plastic which is not a good conductor so less thermal energy is lost

30
Q

higher thermal conductivity means what

A

there will be a higher rate of energy transfer by conduction across the material

31
Q

what are the two layers in modern houses

A

external brick and internal breezeblock

between walls is cavity

32
Q

how do builders correct the high thermal conductivity of homes?

A

pack cavity with insulating material which has low thermal conductivity

33
Q

why do houses have double glazed windows

A

they have a low thermal conductivity

(so less thermal energy passes through and leaves houses interior)

34
Q

other than using materials w low thermal conductivity, how else can we reduce thermal energy transfer?

A

build house w thick walls

34
Q

required practical: specific heat capacity (describe it)

A

place a beaker on a balance and press 0
add oil to the beaker and record the mass of the oil
place a thermometer and an immersion heater into the oil
read the starting temp.
wrap the beaker in insulating foam to reduce thermal energy transfer to the surroundings
connect the joulemeter to the immersion heater
time for thirty minutes
read total n.o of joules that passed into immersion heater
read final temp of oil

35
Q

how to stop thermal energy passing out of the beaker into the air

A

use an insulator with a lower thermal conductivity

36
Q

how to prevent not all thermal energy passing into oil (SH practical)

A

ensure that immersion heater is fully submerged

37
Q

how to prevent incorrect reading of thermometer

A

use an electronic temperature probe

38
Q

how to prevent thermal energy not being spread through the oil

A

stir the oil

39
Q

how to do the thermal insulators practical (2) RP

A

place small beaker inside a large beaker

use kettle to boil some water

transfer 80cm^3 into a small beaker

use cardboard as a lid for large beaker (w hole for thermometer)

bulb of thermometer must be in the hot water

record start temp w a stopwatch

record temp every 3 mins for 15 minutes

repeat experiment using same vol of hot water but different insulating material

use same mass of insulating materials

40
Q

whats the curve called in a temperature/time graph

A

cooling curves

41
Q

the water will cool down _______ with the most effective insulating material

A

most slowly

42
Q

describe practical to test wether thickness of material effects insulation

A

start w beaker containing 80cm^3 of hot water
(lid + thermometer)
measure temp of water every 3 minutes for fifteen minutes
repeat the experiment but wrap 2 layers of newspaper around the beaker
repeat using 4 layers and 6 layers

43
Q

the more layers of newspaper, the_____ the water cools

why?

A

slower

more layers is a more effective thermal insulator than a few layers

44
Q

what are three examples of uses of energy

A

transport, generating electricity , heating

45
Q

what are the 3 main fossil fuels

A

coal, oil, gas

46
Q

whats the advantages of fossil fuels

A

fossil fuels are reliable, always provides energy when we need it

release a great deal of energy

fossil fuels are abundant and relatively cheap

extremely versatile (v portable)

47
Q

what are the disadvantages of fossil fuels

A

releases a huge amount of carbon dioxide

they’re non-renewable as they’re not being replenished

can release other pollutants

48
Q

whats the disadvantages of nuclear power

A

nuclear power is non-renewable, they run on uranium and plutonium

contains highly dangerous radioactive materials. if there’s an accident they could be released to the environment.

decommissioning a power plant takes many years and is extremely expensive

nuclear power plants generate a large amount of highly dangerous radioactive waste. this must be stored for thousands of years before its safe

49
Q

whats the advantages of nuclear power

A

once running it releases NO carbon dioxide so doesn’t contribute to climate change

its v reliable. It generates lots of electricity exactly when we want it

50
Q

The uk has _______ of coal. Up until 1950s almost ____________ generated by Uk came from _______

A

abundant reserved of coal

all of the electricity

burning coal

51
Q

coal and coal gas were also used for almost all ____ and cooking in the UK

A

heating

52
Q

in the 1950s, nuclear power came online and by the 1980s this produces around ____ of the uks electricty

A

20%

53
Q

in the 1970’s the Uk became a big producer of what?

this began to replace ____

A

oil and gas

coal for electricity generation

54
Q

what are the advantages of burning gas over coal?

A

generates less carbon dioxide than burning coal, this contributes less to climate change

gas-fired power stations are flexible, they have a short start up time whereas coal fired power stations have a long start up time

55
Q

what does a short start up time mean

A

they can be switched on quickly during periods of high demand

56
Q

what was an economic factor of using fossil fuels

A

v cheap, switching from them could cost money and cost jobs

57
Q

in 2005, the Kyoto Protocol committed countries to____

A

reducing greenhouse gas emissions

58
Q

why is nuclear power ideal

A

we need a baseload (a constant supply of electricity that’s on all the time)

59
Q

what can we use gas-fired power stations to provide what

A

emergency power in times of peak demand

60
Q

what types of gas provide what in Uk energy

A

renewables provide the bulk of our electricity , nuclear provides a baseload and gas provides electricity during periods of peak demand

61
Q

what is a renewable energy resource

A

a resource that is being or can be replenished as its used

62
Q

name the types of renewable energy

A

wind, solar, hydroelectric, tidal, biofules, geothermal, wave.

63
Q

what are the advantages of renewable energy

A

will never run out

do not add CO2 to the atmosphere so don’t contribute to climate change

64
Q

whats the disadvantage of wind and solar power

A

not reliable, some days are not windy/ sunny

65
Q

whats the advantage of hydroelectric

whats the disadvantage

A

v reliable

habitats are destroyed when dams are built and valleys are flooded

also only useful in countries w lots of rivers so not suitable for uk

66
Q

whats the advantage of tidal power

whats the disadvantage

A

its extremely reliable
(atm the uk doesn’t generate any electricity from it)

may be harmful to wildlife

67
Q

whats the advantage of wave power
whats the disadvantage

A

wave power is reliable and has huge potential in the UK which has an extensive coastline

its v small scale and experimental atm

68
Q

what is geothermal energy

A

geothermal energy uses heat from the earth to generate electricity and heat buildings

69
Q

whats the advantage of geothermal
whats the disadvantage

A

v reliable

not used much in the UK

70
Q

what are biofuels produced from

A

plant materials

71
Q

whats the advantages of biofuels
whats the disadvantage

A

don’t add EXTRA carbon dioxide to the atmosphere so are carbon neutral
&
potentially v useful as we can use them to power vehicles such as cars and buses.

if we use land to grow crops for fuel, that could push up the price of food

GCSE Physics <3 (12 decks)

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