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Physics AQA > P1 Energy > Flashcards

P1 Energy Flashcards

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1
Q

What is the equation for kinetic energy? Give SI units for all quantities involved.

A

1⁄2 m v2
1⁄2 x Mass × (Velocity)2
Energy (J), Mass (kg), Velocity (m/s)

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2
Q

What is the equation for elastic potential energy? Give Sl units for all quantities involved.

A

1⁄2k x2
1⁄2xSpring Constant × (Extension)2
Energy (J), Spring Constant (N/m), Extension (m)

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3
Q

What is the equation for gravity potential energy? Give Sl units for al quantities involved.

A

mgh
Mass x Gravitational Field Strength x Height
Energy (J), Mass (kg), Gravitational Field Strength (N/kg), Height (m)

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4
Q

Define 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

State the units for Specific Heat Capacity

A

J/°C/kg
Joules/Degree Celsius/Kilogram

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6
Q

What is the definition of ‘Power’?

A

The rate at which energy is transferred (or rate at which work is done).

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7
Q

State two equations for power. Give Sl units for al 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 changes involved when a ball is thrown upwards and then returns to its starting position. Ignore air resistance.

A
  • Upwards: KE is converted to GPE
  • Peak: Maximum GPE, zero KE
  • Downwards: GPE is converted to KE

KE (Kinetic Energy), GPE (Gravitational Potential Energy)

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10
Q

Two motors lift the same mass through the same height. Motor A does this in half the time of Motor B.
Which dissipates the most power?

A

Motor A.
The energy transferred is the same but the time taken is less (P = E/t).

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11
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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12
Q

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

A
  • Kinetic energy decreases since ti is converted to elastic potential energy
  • Since KE is proportional to (velocity)2, as KE decreases, so does velocity.
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13
Q

Give examples of chemical energy stores.

A
  • Food
  • Fuel (eg. wood, coal, petrol)
  • Batteries
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14
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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15
Q

State the law of energy conservation.

A

Energy cannot be created or destroyed (it can only be transferred into different forms).

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16
Q

State any changes ni 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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16
Q

What is waste energy?

A

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

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17
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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18
Q

State two equations to calculate efficiency.

A

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

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19
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)
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20
Q

State the consequence for energy transfer of a material with a igh thermal conductivity.

A

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

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21
Q

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

A
  • The thickness of the walls
  • The thermal conductivity of the walls
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22
Q

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

A

Lower, meaning less energy transfers through them.

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23
Q

State three methods of reducing heat loss in a building.

A
  1. Double glazing
  2. Loft and wal insulation
  3. Thicker walls
24
Q

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

A

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

25
Q

How can the efficiency of a radiator be improved?

A

Installing metal foil sheets behind the radiator to reflect the heat back into the room rather than ti being absorbed into the walls.

26
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.

27
Q

What is a renewable energy resource?

A

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

28
Q

Give four examples of renewable energy resources.

A
  1. Wind Energy
  2. Hydro-Electricity
  3. Tidal Energy
  4. Solar Energy
29
Q

Give an example of a non-renewable energy resource.

A

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

30
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
30
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
31
Q

State 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
32
Q

State 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
33
Q

State 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
33
Q

How does hydroelectric power produce energy?

A
  • Rainwater collects behind a dam
  • When this water is released, ti is used to turn a turbine
  • This turbine turns a generator which
    produces electricity
34
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
35
Q

State three disadvantages of nuclear power.

A
  1. Produces nuclear waste which is harmful to humans & must be safely stored for centuries.
  2. Non-Renewable energy source
  3. Risk of nuclear accidents, which have fatal consequences on humans and the environment
36
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
36
Q

What are the disadvantages of hydroelectric power?

A
  • The dam may cause flooding
  • It can cost a lot to install the required
    infrastructure
37
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
38
Q

Give an example of a social factor 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)

39
Q

Closed System:​

A

A system that experiences no net change in its total energy when energy transfers occur within it.

40
Q

Efficiency:

A

​The ratio of useful output energy transfer to total energy input.

41
Q

Conservation of Energy:​

A

The law that energy can be transferred, stored or dissipated but never created or destroyed.

42
Q

Elastic Potential Energy:

A

​The store of energy that stretched or compressed objects experience. It is directly proportional to the stiffness constant and to the square of the extension or compression.

43
Q

Fossil Fuels:​

A

Coal, oil and gas.

44
Q

Gravitational Potential Energy:

A

The store of energy that all raised matter has. It is directly proportional to the mass of the object, the distance that it is risen and the gravitational field strength at that point.

45
Q

Kinetic Energy:

A

The store of energy that all moving matter has. It is directly proportional to the object’s mass and to the square of its velocity.

45
Q

Power:

A

The rate at which energy is transferred, or at which work is done.

46
Q

Joule:​

A

The unit used for energy. Equal to the work done when a force of one Newton acts over a distance of one metre.

47
Q

Renewable Energy Resource:

A

​An energy resource that can be replenished whilst it is being used.

48
Q

Specific Heat Capacity:

A

​The amount of energy required to raise the temperature of 1kg of a substance by 1°C.

49
Q

Spring Constant:

A

A measure of a spring’s stiffness. The greater the value, the greater the force required to stretch or compress the spring by a given distance.

50
Q

System:​

A

A single, or group, of objects.

51
Q

Thermal Conductivity:

A

The higher this value is for a given material, the higher the material’s rate of energy transfer via conduction will be.

52
Q

Waste Energy:​

A

Energy that isn’t usefully used for the purpose of the system.

53
Q

Watt:

A

A unit of power. One Watt is equivalent to one joule of work being done in one second.

54
Q

Work Done:

A

The energy transferred when a force acts over a distance.

Physics AQA (4 decks)

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