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GCSE AQA Physics > Topic 1 - Energy > Flashcards

Topic 1 - Energy Flashcards

1
Q

What are the 8 energy stores that you need to know?

A
  1. Thermal energy stores
  2. Kinetic energy stores
  3. Gravitational potential energy stores
  4. Elastic potential energy stores
  5. Chemical energy stores
  6. Magnetic energy stores
  7. Electrostatic energy stores
  8. Nuclear energy stores
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2
Q

Define

closed system.

A

a system in which neither matter nor energy can enter or leave

the net change in the total energy of a closed system is alway zero

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3
Q

What is the equation for

Kinetic Energy?

(involving mass, velocity and kinetic energy)

A

KE = 1/2(mv^2)

Kinetic Energy (J) = 1/2 (mass (kg) x speed (m/s)^2)

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4
Q

What is the equation for

Gravitational Potential Energy?

(involving field strength, height, mass and gpe)

A

GPE = mgh

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

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5
Q

What is the equation for

Elastic Potential Energy?

(involving spring constant, extension and epe)

A

EPE = 1/2 (ke^2)

EPE (J) = 1/2 (spring constant (N/m) x extension (m)^2)

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6
Q

Define

specific heat capacity.

A

the amount of energy needed to raise the temperature of 1kg of a substance by 1°C

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7
Q

What equation links

specific heat capacity, energy transferred, mass and temperature?

A

ΔE = mcΔT

Change in thermal energy (J) = mass (kg) x specific heat capacity (J/kg°C) x temperature change (°C)

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8
Q

What is the

conservation of energy principle?

A

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

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9
Q

What is

power?

And what is it measured in?

A

the rate of energy transfer or the rate of doing work

it is measured in watts

1 watt = 1 joule of energy transferred per second

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10
Q

What equation links

energy, power and time?

A

P = E/t

Power (W) = Energy transferred (J) / time (s)

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11
Q

What equation links

time, power and work done?

A

P = W/t

Power (W) = Work done (J) / time (s)

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12
Q

Define

conduction.

A

the process where vibrating particles transfer energy to neighbouring particles

(this occurs mainly in solids because liquids and gases are much more free to move around)

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13
Q

Define

thermal conductivity.

A

a measure of how quickly energy is transferred through a material by conduction

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14
Q

Define

convection.

A

the movement of high energy particles from warmer to cooler regions

(this only occurs in liquids and gases because the particles aren’t able to move in solids)

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15
Q

Describe how a

radiator creates convection currents.

(6 steps)

A
  1. Energy is transferred from the radiator to the nearby air particles by conduction (the air particles collide with the radiator surface).
  2. The air by the radiator becomes warmer and less dense.
  3. This warm air rises and is replaced by cooler air.
  4. The cooler air is then heated by the radiator.
  5. At the same time, the previously heated air transfers energy to the surroundings. It thus cools, becomes denser and sinks.
  6. This cycle repeats, causing a flow of air to circulate around the room - this is a convection current.
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16
Q

What does a

lubricant do?

A

reduces the friction between objects’ surfaces when they move

(these are usually liquids (like oil), so that they can flow easily between objects and coat them)

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17
Q

What are some things you can do to

prevent energy losses from heating in a house?

(2 things)

A
  • have thick walls that are made from a material with a low thermal conductivity
  • use thermal insulation
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18
Q

What are some examples of

thermal insulation?

(4)

A
  • cavity walls
  • loft insulation
  • double-glazed windows
  • draught excluders
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19
Q

What are

cavity walls?

and how do they work as thermal insulation?

A

an inner and an outer wall with an air gap in the middle
~~~
the air gap reduces the amount of energy transferred by conduction through the walls

cavity wall insulation (where the cavity wall air gap is filled with foam), can also reduce energy transfer by convection in the wall cavity

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20
Q

How does loft insulation work as thermal insulation?

A

it reduces convection currents being created in lofts

21
Q

How do double-glazed windows work as thermal insulation?

A

they work in the same was as cavity walls - they have an air gap between two sheets of glass to prevent energy transfer by conduction through the windows

22
Q

How do draught excluders work as thermal insulation?

A

they reduce energy transfers by convection around doors and windows

23
Q

What is the equation for

efficiency?

A

useful output (power/energy)x100
~~~~~~~~~~~~~~~~~~~~~~~~~~
input (power/energy)

24
Q

What device is 100% efficient?

A

electric heaters

all the energy in the electrostatic energy store is transferred to “useful” thermal energy stores

25
# What are the three main fossil fuels?
- coal - oil - (natural) gas
26
# What are the positives and negatives of non-renewable energy resources? | (2+, 1-)
+**reliable** -will 'run out' one day -do **damage** to the environment
27
# What are some examples of renewable energy sources? | (7 examples)
- the sun (solar) - wind - water waves - hydro-electricity - bio-fuel - tides - geothermal
28
# What are the positives and negatives of renewable energy resources? | (2+, 2-)
+will **never run out** - the energy can be '**renewed**' as it is used +most of them **damage** the environment, but this is less than non-renewables -**don't** provide much **energy** -some are **unreliable** (because they depend on weather)
29
How is wind power generated? | (3 steps)
1. **Wind turbines** are put up in **exposed places**. 2. Each turbine has a **generator** inside it. 3. The rotating blades turn the generator and produce **electricity**.
30
# What are the positives of wind power? | (and wind turbines)(4)
- **no pollution** (except for manufacture) - **no fuel costs** - **minimal running costs** - **no permanent damage** to the landscape
31
# What are the negatives of wind power? | (and wind turbines)(5)
- **spoil the view** - can be **very noisy** - turbines stop **when the wind stops** or if the wind is **too strong** - it's **impossible** to **increase supply** when there's **extra demand** - the **initial costs are quite high**
32
How is solar power generated?
**solar panels** generate electric currents directly from sunlight
33
# What are the positives of solar power? | (and solar panels)(4)
- **no pollution** (except for manufacture) - **very reliable source** of energy in sunny countries - **free** energy - **very low running costs**
34
# What are the negatives of solar power? | (and solar panels)(3)
- only a source of energy in the **daytime** - you **can't increase the power output** when there is **extra demand** - **high initial costs**
35
# What are the positives of geothermal power? | (2)
- **reliable** - does very little damage to the **environment**
36
# What are the negatives of geothermal power? | (2)
- **aren't** very many **suitable locations** for power plants - the **cost** of building a power plant is often **high** compared to the **amount** of energy it produces ## Footnote (only **possible** in **volcanic ares** or where **hot rocks** lie quite near to the **surface**)
37
# What are the positives of hydro-electric power? | (5)
- **no pollution** - can provide an **immediate response** to an increased demand for electricity - no problem with **reliability** (except in times of **drought**) - **no fuel costs** - **minimal running costs**
38
# What are the negatives of hydro-electric power? | (4)
- there is a **big impact** on the **environment** due to the flooding of the valley - there is possible **loss of habitat** for some species - the reservoirs can look very **unsightly** when they **dry up** - **initial costs** are **high**
39
How is wave power generated? | (2 steps)
1. **Lots** of small **wave-powered turbines** are placed **around the coast**. 2. The moving turbines are connected to a generator.
40
# What are the positives of wave power? | (3)
- **no pollution** - **no fuel costs** - **minimal running costs**
41
# What are the negatives of wave power? | (5)
- **disturbs the seabed** and the **habitats** of marine animals - **spoils the views** - can be a **hazard to boats** - **fairly unreliable**, since waves tend to die out when the **wind drops** - **initial costs are high**
42
How is tidal power generated? | (3 steps)
1. **Tidal barrages** (**big dams**) are built across **river estuaries**, with turbines in them. 2. As **tide comes in** it fills up the estuary. 3. The water is then allowed out through turbines at a **controlled speed**.
43
# What are the positives of tidal power? | (5)
- **no pollution** - pretty **reliable** (occur twice a day **without fail**) - **no fuel costs** - **minimal running costs** - has the potential for generating a **significant amount** of energy
44
# What are the negatives of tidal power? | (6)
- **prevents free access by boats** - **spoils the view** - **alters the habitat** of the wildlife - **height** of the tide is **variable** so energy provided will vary significantly over the year - **moderately high initial costs** - can only be used in **some suitable estuaries**
45
# What are the positives of bio-fuels? | (2)
- supposedly **carbon neutral** - fairly **reliable**
46
# What are the negatives of bio-fuels? | (5)
- cannot respond to **immediate energy demands** - the **cost** to refine **bio-fuels** is **very high** - growing crops specifically for bio-fuels may mean there isn't enough **space** or **water** to meet the demands for crops that are grown for **food** - in some regions, large areas of **forest** have been **cleared** to make room to grow **bio-fuels**, resulting in lots of species losing their **natural habitats** - the **decay** and **burning** of this vegetation also increases **carbon dioxide** and **methane** emisssions
47
# What are the positives of non-renewable energy sources? | (e.g. nuclear energy, fossil fuels)(6)
- **reliable** - the power plants can respond **quickly** to **changes in demand** - running costs **aren't that expensive** - **fuel extraction costs** are fairly low - **nuclear power** is **clean** - nucelar **fuel** is **relatively cheap**
48
# What are the negatives of non-renewable energy sources? | (e.g. nuclear energy, fossil fuels)(7)
- **slowly running out** - **high set up costs** compared to other energy resources - coil, oil and gas release carbon dioxide into the atmosphere when they're burned (adding to the **greenhouse effect** and **global warming**) - burning coal and oil releases **sulfur dioxide** (which causes **acid rain**) - **coal mining** makes a mess of the landscape - the **view** can be **spoilt** by fossil fuel power plants - **oil spillages** cause **serious environmental problems**, affecting mammals and birds that live in and around the sea
49
# What are the negatives of nuclear power? | (3)
- **nuclear waste** is very dangerous and difficult to **dispose of** - the **overall cost** of nuclear power is **high** due to the cost of the power plant and final **decomissioning** - **nuclear power** always carries the risk of a major **catastrophe** like the **Fukushima disaster** in Japan

GCSE AQA Physics (8 decks)

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