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My Physics > Section 4: Energy resources and energy transfer > Flashcards

Section 4: Energy resources and energy transfer Flashcards

1
Q

Solar cells

A

Pro:

  • Free and renewable
  • No pollution
  • Can generate electricity from photovoltaic cells

Con:

  • uk sunshine unreliable and limited
  • confined to daylight hours
  • relatively expensive to manufacture
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2
Q

Wind

A

Pro:

  • renewable
  • emission free and quick to build
  • no fuel costs

Con:

  • noise and visual pollution
  • more expensive than fossil fuels
  • wind levels fluctuate
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3
Q

Tidal

A

Pro:

  • renewable
  • emission free
  • predictable

Con:

  • development costs
  • harmful to aquatic life
  • very few ideal locations
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4
Q

Hydroelectric

A

Pro:

  • renewable
  • no CO2 emissions
  • very cheap once dam has been built

Con:

  • natural flow hydro reliant on rainfall and vulnerable to droughts
  • pump storage relies on off peak electricity to pump water back uphill
  • environmental and social impact of large dams
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5
Q

Oil

A 
Pro:
-reliable
-cheap to extract
-well established 
Con:
-CO2 emission
-non-renewable 
-price instability 
-reliance on politically unstable countries
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6
Q

Nuclear

A 
Pro:
-reliable and efficient 
-minimal CO2 emission after construction
-not vulnerable to price fluctuations
Con: 
-danger of nuclear waste, safety
-huge cost of building/ decommissioning reactor 
-planning/building takes years
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7
Q

Biofuels

A

Pro:
-carbon neutral(carbon released balance carbon absorbed)
-suitable crops can be grown in UK
Con:
-space required to grow crops
-greenhouse gases in harvesting/transporting crops
-inefficient compared to fossil fuels

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8
Q

Coal

A

Pro:

  • cheap and reliable
  • abundant, UK has large reserves
  • decline of SO4 (acid rain) emissions last 29 years
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9
Q

Gas

A 
Pro:
-reliable 
-cleaner than coal
-lower CO2 emission 
-uk North Sea reserves
Con:
-significant CO2 emissions
-reserves running out fast so growing independence on imports and rising prices
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10
Q

Landfill gas

A

Pro:
-burning it reduces methane(contribution to climate change)

Con:
-releases CO2 and nitrogen oxide gases

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11
Q

Define work done

A

Work done = force applied x distance
(in joules) (Newtons) (metres)
W = F x d

Work done is when energy is transferred from one from to another. e.g lifting an object

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12
Q

Gravity potential energy

  • Equation
  • change in GPE
A

GPE = m x g x h

(J) g) (10N/kg) (m)

When we do work to give an object GPE we are lifting it above Earth’s surface.

△GPE = m x g x △h

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13
Q

Kinetic energy

A

-The amount of energy possessed by a moving object
-This depends on the mass and speed of the object
KE = 1/2 mv ²
KE = 1/2 mass x velocity ²
(J) (Kg) (m/s)

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14
Q

Power

A

The rate of which work is done

P = W/t
Power = work done/time
watt) (J) (s
1 watt = 1 joule transferred/second

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15
Q

Law of conservation of energy

A

Energy cannot be created/destroyed, only transferred from one form to another.

e.g Electric motor
electric→KE +( heat + sound)
wasted-dissipates into atmosphere

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16
Q

Efficiency

A

Efficiency = useful energy output/ x 100
total energy input

Can be represented by a Sankey diagram

17
Q

Work done/GPE example:

  1. Calculate the WD lifting a 5 kg brick 10m into the air
  2. What’s its GPE?
A

W = F x d
The force we need is the weight of the object

force = 5 x 10 = 50N
WD = 50 x 10 = 500J

When i ve done the work the brick has GPE
△GPE = mg △h
5 x 10 x 10 = 500J
So the gain in GPE = WD

18
Q

What happens to wasted energy?

A

Every energy transfer produces heat which is dissipated into the atmosphere

(spreads out in air)

19
Q

Energy changes:

  • electric motor
  • recharging battery
  • speaker
  • microphone
  • diving
A
  • electric motor: electrical → kinetic + heat + sound
  • recharging battery: electrical → chemical + heat
  • speaker: electrical → sound
  • microphone: sound → electrical
  • diving: GPE → kinetic

Note: heat is always a product of energy transfer

20
Q

Energy in different forms

A
  • Sound energy (particles vibration)
  • Heat energy
  • Light energy
  • Chemical energy (burning fuels and food)
  • Kinetic energy (moving objects)
  • Nuclear energy (stored in the nucleus of an atom)
  • Gravitational potential energy (objects above ground)
  • Electrical energy
  • Elastic potential energy/strain energy (stretched objects)
21
Q

Renewable fuel

A

Fuels produced from renewable resources that we have an infinite supply of

22
Q

Non-renewable fuel

A

Fues produced from non-renewable resources that we have a finite supply of

23
Q

What is a fuel

A

A concentrated source of energy

24
Q

Where are nuclear power stations built? Why?

A

Near a constant supply of water, in an isolated area

Because of their immense size and safety considerations

25
Q

What happens after 40-50 years to a nuclear power station?

A

It ends its productive life, and needs to be shut down in a process called decommissioning. This takes years and costs billions of pounds

26
Q

Demand for electricity

A

Varies from day to day. This can be predicted to an certain extent.

27
Q

Examples of a predictable demand for electricity

A
  • surge in early morning/evening

- greater demand in winter than summer

28
Q

Examples of an unpredictable demand for electricity

A
  • a storm

- break in-between a football match

29
Q

Start up time of different energy resources

A

Nuclear power station: Weeks (not stopped unless absolutely necessary )

Coal, Oil and Gas : typically a few hours

Hydroelectric: seconds (particularly good for supplying at peak demand times )

Wind: depends on wind

Tide: predictable when available

30
Q

Sankey diagrams

A

Check iPad

31
Q

What is energy?

A

Ability to do work

My Physics (12 decks)

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