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GCSE Physics > Energy > Flashcards

Energy Flashcards

1
Q

What is the equation for kinetic energy?

A

kinetic energy = 1/2 x mass x speed^2

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2
Q

What is the equation for elastic potential energy?

A

Elastic potential energy (J) = 0.5 x spring constant (N/m) x (extension (m))^2

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3
Q

What is the equation for gravitational potential energy?

A

gravitational potential energy = mass x gravitational field strength x height

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4
Q

What is the ‘specific heat capacity’ of a substance?

A

The amount of energy needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius

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5
Q

What are the units for specific heat capacity?

A

Joules per kilogram per degree Celsius (J/kg °C)

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6
Q

What is the definition of ‘power’?

A

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

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7
Q

State two equations for power. Give SI units for all quantities involved.

A

power = energy transferred/time
power = work done/time
Energy (J), Work Done (J), Time (s)

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8
Q

What is the unit of power?

A

Watt (W)

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9
Q

Describe the energy transfers for a bungee jumper.

A

● When falling, the GPE is converted to KE of jumper
● As the cord tightens, KE is converted and stored as Elastic Potential Energy (EPE)
● At lowest point, the jumper’s initial GPE equals the EPE stored in the cord

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10
Q

Explain why a bungee jumper slows down once the cord begins to stretch.

A

● Kinetic energy decreases since it is converted to elastic potential energy
● Since KE is proportional to (velocity)², as KE decreases, so does velocity.

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11
Q

State 4 different stores of energy.

A
  1. Kinetic Energy
  2. Gravitational Potential Energy
  3. Elastic Potential Energy
  4. Chemical Energy
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12
Q

Give examples of kinetic energy stores

A

Compressed springs and inflated balloons

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13
Q

Give examples of gravitational potential energy stores

A

Aeroplanes and kites

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14
Q

Give examples of elastic potential energy

A

A bent diving board and archers stretched bow

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15
Q

Give examples of chemical energy stores

A

food, fuel and batteries

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16
Q

What is the law of energy conservation?

A

Energy cannot be created or destroyed

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17
Q

State any changes in the total energy of a ball that is kicked, assuming that no external forces act.

A

The total energy of the system remains constant due to the conservation of energy.

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18
Q

What is waste energy?

A

The energy that is not used by the device for its desired purpose.

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19
Q

Describe the energy changes that occur in a filament light-bulb

A

● Electrical energy is transferred into light and heat energy
● Light is a useful energy form, heat is waste energy

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20
Q

What are two equations to calculate efficiency?

A

=Useful Output Energy Transfer/Total Input Energy Transfer
=Useful Power Output/Total Power Output

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21
Q

How can the efficiency of a system be increased?

A
  1. Reducing waste output (by lubrication, thermal insulation etc.)
  2. Recycling waste output (eg. recycling thermal waste energy as input energy)
22
Q

What is the consequence for energy transfer of a material with a high thermal conductivity?

A

The rate of energy transfer through the material is higher than for a material with a lower thermal conductivity.

23
Q

Do double-glazed windows have a higher or lower thermal conductivity than single-glazed windows?

A

Lower, meaning less energy transfers through them.

24
Q

What key factors affect the rate of cooling of a building?

A

● The thickness of the walls
● The thermal conductivity of the walls

25
Q

What are three methods of reducing heat loss in a building?

A
  1. Double glazing
  2. Loft and wall insulation
  3. Thicker walls
26
Q

How can the efficiency of mechanical machine with moving parts be improved?

A

Lubricate any moving parts to reduce the friction and therefore energy loss due to heating.

27
Q

How can the efficiency of a radiator improved?

A

Insulting metal foil sheets behind the radiator to reflect the heat back into the room rather than it being absorbed into the walls

28
Q

How can the efficiency of boiling water in a pan be improved?

A

By placing a lid on the pan to reduce the heat loss from the top.

29
Q

What is a renewable energy resource?

A

An energy source which can be replenished as it is being used up.

30
Q

What are four examples of renewable energy resources?

A
  1. Wind Energy
  2. Hydro-Electricity
  3. Tidal Energy
  4. Solar Energy
31
Q

What is an example of non-renewable energy resource?

A

Fossil fuels (for example coal, oil and gas).

32
Q

What are the advantages of generating power using gas rather than coal?

A

● Flexible Generation: Gas power stations have short start-up times so can be switched on/off more readily
● Lower emissions of carbon dioxide

33
Q

What are two disadvantages of using renewable energy resources to generate power?

A

● Output often determined by external factors (like wind speed), so supply is uncertain
● Generating power through other means is often more efficient and economically beneficial

34
Q

Explain the environmental impacts of burning fossil fuels

A

● Carbon Dioxide contributes to the greenhouse effect, and causes global warming
● Sulphur Dioxide leads to acid rain, which can damage buildings and crops

35
Q

What are three advantages of fossil fuels as an energy resource?

A
  1. Reliable: Not dependent on external factors so can generate power anytime
  2. Can produce large amounts of energy for a given quantity
  3. Still relatively abundant, so cost-effective
36
Q

What are three advantages of nuclear power?

A
  1. Very large amounts of energy for relatively small quantities of fuel
  2. Doesn’t release greenhouse gases and so doesn’t contribute to climate change
  3. Low fuel costs
37
Q

What are three advantages of nuclear power?

A
  1. Very large amounts of energy for relatively small quantities of fuel
  2. Doesn’t release greenhouse gases and so doesn’t contribute to climate change
  3. Low fuel costs
38
Q

How does hydroelectric power produce energy?

A

● Rainwater collects behind a dam
● When this water is released, it is used to turn a turbine
● This turbine turns a generator which
produces electricity

39
Q

What are some disadvantages of using biofuels?

A

● When plants are burned or decay they release CO2
● In order to grow biofuels, you need to destroy land which leads to problems because:
● The land could have been natural habitats
● Destroying land may involve burning plants growing on it, which would release CO2
● Growing biofuels reduces the land available for growing food

40
Q

What are the advantages of tidal energy sources?

A

● They do not produce greenhouse gases
● They are quite reliable, as tides happen twice a day
● They are cheap to run as tides are natural, and so are free

41
Q

What are the disadvantages of hydroelectric power?

A

● The dam may cause flooding
● It can cost a lot to install the required infrastructure

42
Q

What are some advantages of solar panels?

A

● They don’t cause harm to the environment
● They are a renewable resource
● They can be used in remote areas where other types of energy are less accessible

43
Q

What are examples of social factors which may act as a deterrent for certain types of energy production?

A

● Visual Pollution
● Sound Pollution
(both of these are disadvantages of wind farms)

44
Q

What are thermal conductors?

A

Materials with a low specific heat capacity so heat up and cool down quickly

45
Q

What are thermal insulators?

A

Materials with a high specific heat capacity so heat up and cool down slowly

46
Q

How do you improve energy?

A

Reduce the amount of energy that a device wastes or dissipates to the surroundings

47
Q

What ways could you improve efficiency?

A

1) Lubricate mechanical devices to reduce the friction between moving parts of the machine
2) Insulate heating devices to reduce the dissipation of thermal energy to the surroundings

48
Q

What is conduction?

A

When heat is transferred through a material due to vibrating particles colliding and transferring energy from one particle to another
Image: Conduction

49
Q

What is convection?

A

When heat is transferred through a moving liquid or gas due to differences in densities

50
Q

What is radiation?

A

When heat is transferred from a hot object due to the object emitting infrared (heat) radiation

GCSE Physics (8 decks)

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