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Physics GCSE > topic 2 - conservation of energy > Flashcards

topic 2 - conservation of energy Flashcards

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1
Q

kinetic energy store

A

the energy of a moving object

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2
Q

what does kinetic energy depend on

A

mass and speed

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3
Q

kinetic energy formula

A

KE = 1/2 x mass x speed^2

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4
Q

gravitational potential energy store

A

potential energy an object has due to the action of gravity on it
the energy gained by an object as it is lifted

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5
Q

what does GPE depend on

A

mass, height, gravitational field strength

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6
Q

gravitational potential energy formula

A

GPE = mass x gfs x change in vertical height

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7
Q

thermal energy store

A

energy of an object due to its temperature

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8
Q

elastic potential store

A

energy of a stretched spring or elastic band

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9
Q

chemical energy store

A

energy within a chemical substance

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10
Q

magnetic energy store

A

energy due to the force of attraction between two magnets

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11
Q

electrostatic energy store

A

energy due to force of attraction between two electrostatic charges

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12
Q

nuclear energy store

A

energy contained within an atom’s nucleus

energy released by two atomic nuclei in nuclear reactions

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13
Q

conservation of energy

A

energy can be stored, transferred and dissipated but never created or destroyed

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14
Q

what happens to energy in a closed system

A

in a closed system, total energy never changes

there is no NET change to the total energy

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15
Q

in what 4 ways can energy be transferred

A

mechanically
electrically
by heating
by radiation

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16
Q

how can energy be transferred mechanically

A

transferred by a force acting on an object

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17
Q

how can energy be transferred electrically

A

transferred by a charge doing the work

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18
Q

how can energy be transferred by heating

A

energy transferred from a hotter object to a cooler object

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19
Q

how can energy be transferred by radiation

A

energy is transferred by waves

20
Q

energy transfers when an object is projected upwards/up a slope

A

work done against gravity

kinetic energy is transferred MECHANICALLY to gpe

21
Q

energy transfers when a moving object hits an obstacle and example

A

eg. ball hitting bat
bat transfers kinetic energy mechanically to the ball
some energy is mechanically transferred to the thermal energy stores
rest of energy is transferred as sound

22
Q

energy transfers when an object is being accelerated at a constant force and example

A

eg. rock dropping from a cliff

GPE is transferred mechanically to the kinetic energy store

23
Q

energy transfers when a vehicle is slowing down

A

kinetic energy transferred mechanically and by heating to the thermal energy store of the road and the car

24
Q

energy transfers when a kettle is boiling water

A

energy transferred electrically to the heating element

energy transferred by heating from the element to the thermal energy store of the water

25
Q

what happens when work is done mechanically

A

there is often friction
the friction has to be overcome and the energy for this is transferred from kinetic energy to thermal energy
energy is often dissipated by heating (wasteful)

26
Q

what tends to dissipate

A

heat, light and sound energy tend to dissipate

it is hard to gather the spreadout energy so the energy is less useful

27
Q

what happens when energy is transferred from one store to another

A

when energy is transferred from one store to another, some energy is lost

28
Q

efficiency

A

how much useful energy you get from a device compared to the energy that went into it

29
Q

efficiency formula

A

efficiency = useful energy transferred (J)/ total energy supplied (J)

30
Q

how can efficiency be improved in a mechanical system

A

to reduce unwanted energy produced in a mechanical system, you could reduce friction

  • you could add bearings to prevent parts from rubbing directly together
  • lubrication
31
Q

how can efficiency be improved in a electrical system

A

to reduce unwanted energy produced in an electrical system, you could reduce resistance

  • use lower resistance parts/components
  • lower the electrical current
32
Q

lubrication

A

lubrication can be used to reduce friction between two surfaces as they move

33
Q

what does thermal insulation do

A

thermal insulation reduces the thermal energy lost by conduction

34
Q

thermal conductivity

A

how well a material transfers energy via conduction
metals/solids have high thermal conductivity
gases have low thermal conductivity

35
Q

to reduce rate of cooling, what should walls be like

A

walls should be thick and have low thermal conductivity

36
Q

3 types of thermal insulation in buildings

A

loft insulation with fibreglass in
double glazed windows - two sheets of glass with air gap in-between
cavity walls - inner and outer walls with air in-between

37
Q

energy resources

A

large banks of energy that can be transferred into a form that can be used by society

38
Q

non-renewable energy resources (def + examples)

A

resources that will run out once day, natural resources that form underground over millions of years
eg.. coal, oil, natural gas

39
Q

non-renewable energy resources features

A

typically burnt to provide energy
provide most of our energy
do damage to the environment

40
Q

renewable energy resources (def + examples)

A

resources which will never run out as the energy used can be ‘renewed’
eg.. solar, wind, hydroelectricity, biofuel, tides

41
Q

renewable energy resources features

A

don’t provide as much energy
reliant upon weather
still damage the environment, just to a lesser extent

42
Q

what is non-renewable energy used for generally

A

non-renewable energy is used for more large-scale energy supplies due to the large energy output per kilogram of fuel

43
Q

why have renewable resources become more important

A

because of the finite lifetime of fossil fuels

44
Q

trends in energy resource use

A

during the Industrial revolution, fossil fuels were an important source of energy as it was easy to mine and provided lots of energy
since the start of the 21st century, electricity use has been slowly decreasing as appliances have become more efficient and we have been more careful with energy use in our homes

45
Q

how is our energy produced

A

some of our energy is produced using fossil fuels (which we also burn to fuel cars and heat homes) and from nuclear power

46
Q

what is the aim in terms of energy resources as we move forwards

A

the aim is to begin to use more renewable resources due to pressure on the government from the public and other countries

Physics GCSE (10 decks)

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