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physics. > Energy > Flashcards

Energy Flashcards

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1
Q

What are the different types of energy stores?

A 
›thermal.
› kinetic.
› gravitational potential.
› elastic potential.
› chemical.
› magnetic.
› electrostatic.
› nuclear.
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2
Q

Describe how energy can be transferred.

A

› when a system changes, energy is transferred and it can be transferred into or away from the system between different objects in the system or between different types of energy stores.

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3
Q

What is meant by the term ‘system’?

A

A fancy word for a single object such as air in a piston, or a group of objects such as two colliding vehicles that you’re interested in.

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4
Q

What is meant by the term work?

A

Work done is just another way of saying energy transferred.

↳ work can be done when current flows or by a force moving an object.

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5
Q

What does the kinetic energy of an object depend on?

A

The object’s mass and speed as the greater the mass and the faster it’s going, there more energy there will be in its kinetic energy store.

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6
Q

What is an elastic potential energy store?

A

The stretching or squashing of an object which can transfer energy to the elastic potential energy store.

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7
Q

What is the formula to find the elastic potential energy store (J)?

A

Ee = 1/2ke²

Elastic potential energy = 1/2 spring constant x extension.

Ee ⟶ elastic potential energy (J).
k ⟶ spring constant (N/m).
e ⟶ extension (m).

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8
Q

What is meant by useful energy?

A

Useful energy is energy in the place we want it and the form we need it. Useful energy and wasted energy both end up being transferred to the surroundings, which become warmer.

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9
Q

What is meant by wasted energy?

A

Wasted energy is dissipated energy that is stored in a way that is not useful. Useful energy and wasted energy both end up being transferred to the surroundings, which become warmer.

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10
Q

What is meant by the term efficiency?

A

How good a device is at transferring energy input to useful energy output.

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11
Q

How does a phone waste energy?

A

A mobile phone is a system where when you use it, energy is usefully transferees from the chemical energy store of the battery in the phone however some of the energy is dissipated in this transfer to the thermal energy store of the phone which is why your phone may feel warm.

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12
Q

What is specific heat capacity?

A

The amount of energy needed to raise the temperature of 1 kg of a substance by 1ºC.

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13
Q

What is the formula to find the thermal energy store(J)?

A

△E = mc△θ
↳ change in thermal energy = mass x specific heat capacity x temperature change.

△E ⟶ change thermal energy (J).
m ⟶ mass (kg).
c ⟶ specific heat capacity (J/kgºC).
△ ⟶ take away the two temperatures to find temperature change.
θ ⟶ temperature change (ºC).
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14
Q

How is energy supplied to our homes?

A

› non-renewable energy.
↳ natural gas- most widely used fuel for heating homes in the UK which is used to heat water pumped from into the radiators throughout the home.
↳ coal - commons burnt in fireplaces.
↳ electric heaters.
› renewable energy.
↳ a geothermal (or ground source) heat pump - uses geothermal energy resources to heat buildings.
↳ solar water heaters - using sun to heat water which is pumped into radiators in the building.
↳ burning bio-fuel or using electricity generated from renewable energy resources.

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15
Q

How are nuclear fuels used in power stations?

A

Works in a similar way to fossil fuel station where it relies on heat to produce steam and turn a turbine which is then release from a nuclear reaction rather than burning fuel.

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16
Q

What are the 4 advantages of using nuclear fuels?

A

› highest energy density resource.
› one nuclear station replaces 10 fossil fuel stations.
› predictable and reliable and last longer than fossil fuel.
›no harmful gases as water only comes out.

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17
Q

What are the 3 disadvantages of using nuclear fuels?

A

› waste is dangerous for thousands of years and must be stored safely.
› chance of serious nuclear accident.
› expensive to build and maintain.

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18
Q

What are the four types of energy transfer?

A 
> mechanical
   ↳ a force doing work.
> electrical
   ↳ work done by moving charges.
> heating
> radiation
   ↳e.g. light or sound.
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19
Q

What is work done?

A

Energy transferred.

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20
Q

What is meant by the term ‘system’ in energy transfers?

A

A single object or a group of objects.

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21
Q

What is the energy transfers when an arm throws a ball up?

A

Chemical energy store of arm ⟶ force exerted by arm does work ⟶ kinetic energy store of and arm.

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22
Q

What is the energy transfers when a ball is falling?

A

Gravitational potential energy store of ball ⟶ gravitational force does work ⟶ kinetic energy store of ball.

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23
Q

What is the energy transfers when brakes are applied to car wheels?

A

Kinetic energy stores of wheels ⟶ friction does work ⟶ thermal energy stores of surroundings.

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24
Q

What is the energy transfers when a car hits a tree?

A

Kinetic energy store of car ⟶ normal contact force does work ⟶ other energy stores such as elastic potential energy stores of car and tree.

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25
Q

What is the energy transfers when a kettle’s heating element and water?

A

Energy transferred electrically ⟶ thermal energy store of kettle’s heating element ⟶ energy transferred by heating ⟶ thermal energy store of water.

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26
Q

What is the formulae for kinetic energy?

A

E𝚔 = ¹/₂mv²

Kinetic energy = ¹/₂ x mass x speed²
J) (kg) (m/s

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27
Q

What is the formulae for gravitational potential energy?

A

E𝚙 = mgh

Gravitational potential energy = mass x gravitational field strength x height
(J) (kg) (N/kg)
(m)

28
Q

What does the conversation of energy state?

A

Energy can be transferred usually, store or dissipated but not created or destroyed.

29
Q

What is a closed system?

A

No energy (or matter) is transferred in or out of the system, so there is no overall change in total.

30
Q

What is meant by the term ‘power’ in energy?

A

The rate of energy transfer (or rate of doing work).

31
Q

What is the formulae for power?

A

P = E/t
Power = energy transferred / time
(W) (J) (s)

or

P = W/t
Power = work done / time
(W) (J) (s)

32
Q

What is the formulae for efficiency?

A

Efficiency = useful output energy transfer / total input energy transfer x 100.

or

Efficiency = useful power output / total power input x 100.

33
Q

What is meant by the term ‘conduction’?

A

Process where vibrating particles transfer energy to neighbouring particles.

34
Q

What is meant by the term ‘convention’?

A

Where energetic particles move from hotter to cooler regions.

35
Q

What are the two possible ways to decrease how quickly a building cools?

A

> increase thickness of its walls.

> make walls out of material with lower thermal conductivity.

36
Q

What is non-renewable energy resources?

A

Energy resources that will run out one day.

37
Q

What is renewable energy resources?

A

Energy resources that will never run out.

38
Q

What are the three reasons why energy is used?

A

> generate electricity.
heating.
transport.

39
Q

What are the non-renewable resources called?

A

> fossil fuels.

> nuclear power.

40
Q

What are the renewable resources called?

A 
> wind power.
> solar power.
> geothermal power.
> hydro-electric power.
> wave power.
> tidal barrages.
> bio-fuels.
41
Q

Which of the resources are not reliable and why?

A 
> wind power.
  ↳ turbines stop turning when wind stops or is too 
       strong.
> wave power.
   ↳ waves depend on wind.
42
Q

Which of the resources are reliable?

A 
> fossil fuels.
> nuclear power.
> solar power.
> geothermal power.
> hydro-electric power.
> tidal barrages.
> bio-fuels.
43
Q

What are the three types of fossil fuels?

A

> coal.
oil.
(natural) gas.

44
Q

How are fossil fuels used to generate electricity?

A

It is burned.

45
Q

How is nuclear fuel used to generate electricity?

A

It undergoes fission in nuclear reactors.

46
Q

How is wind power used to generate electricity?

A

Wind turns the wind turbines.

47
Q

How is solar power used to generate electricity?

A

Directly from sunlight.

48
Q

How is geothermal power used to generate electricity?

A

From energy from thermal energy stores of underground hot rocks.

49
Q

How is hydro-electric power used to generate electricity?

A

Big dams, built in valley, fill up with water and the water is allowed out through turbines.

50
Q

How is wave power used to generate electricity?

A

Waves move up and down as air is forced through turbines.

51
Q

How is tidal barrages used to generate electricity?

A

Tidal comes in as water builds behind the dam then water is allowed out through the turbines.

52
Q

How are bio-fuels used to generate electricity?

A

It is made form plant products or animal dung and is burned.

53
Q

Why may coal be used?

A

Heating and used to power steam trains.

54
Q

Why may oil be used?

A

To make fuel for cars.

55
Q

Why may (natural) gas be used?

A

Heat water that is pumped into radiators.

56
Q

What are the disadvantages of using fossil fuels?

A

> releases CO₂ contributing to global warming.

> coal and oil releases sulfur dioxide, causing acid rain.

57
Q

What are the disadvantages and advantages of using wind power?

A

> produce no pollution when in use.
noisy.
spoil the view.

58
Q

What is an advantage of using solar power?

A

Produce no pollution when in use.

59
Q

What is an advantage of using geothermal power?

A

Do very little environmental damage.

60
Q

What is a disadvantages and advantage of using hydro-electric power?

A

> produce no pollution when in use.
rotting plants (from flooding the valley)
release methane and CO₂, contributing to global warming.

61
Q

What is a disadvantages and advantage of using wave power?

A

> produce no pollution when in use.
disturb habitats of sea animals.
spoil the view.

62
Q

What is are the disadvantages and advantages of using tidal barrages?

A

> produce no pollution when in use.
disturb habitats of nearby wildlife.
spoil the view.

63
Q

What is a disadvantage of using bio-fuels?

A

in some regions, large areas of forest destroyed to grow bio-fuels, so species lose natural habitats.

64
Q

What is the trend in energy use from 1900 to 2000?

A

Electricity use has increased due to population growth and people began to use electricity for more things.

65
Q

What is the trend in energy use from 2000 onwards?

A

Electricity use is decreasing as appliances are now more efficient and people are more careful with the amount of energy they use.

66
Q

What are the reasons why we’re increasing the use of renewable?

A

> burning fossil fuels is very damaging to the environment.
we need to learn how to get by without non-renewables before they run out.
pressure on governments have led them to introduce renewable energy targets.

physics. (10 decks)

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