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Physics Paper 1 > Topic 1: Energy > Flashcards

Topic 1: Energy Flashcards

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1
Q

1.1

A

Energy Changes in a System

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2
Q

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

A
  • 1/2 x m x v²
  • 1/2 x mass x velocity²
  • Energy (J), Mass (kg), Velocity (m/s)
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3
Q

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

A
  • 1/2 x k x x²
  • 1/2 x spring constant x extension²
  • Energy (J), Spring constant (N/m), Extension (m)
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4
Q

What is the equation for gravity potential energy?
Give SI units for all 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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5
Q

Define the ‘Specific Heat Capacity’ of a substance.

A

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

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6
Q

State the units for Specific Heat Capacity

A
  • J/ºC/kg
  • Joules/Degree Celsius/Kilogram
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7
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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8
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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9
Q

What is the unit of power?

A

Watt (W)

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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 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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12
Q

Describe the energy transfers for a bungee jumper.

A
  • When falling, the gravitational potential energy is converted to kinetic energy of the jumper
  • As the cord tightens, kinetic energy is converted and stored as elastic potential energy
  • At lowest point, the jumper’s initial gravitational potential energy equals the elastic potential energy stored in the cord
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13
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 kinetic energy is proportional to (velocity)², as kinetic energy decreases, so does velocity
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14
Q

Give examples of chemical energy stores.

A
  • Food
  • Fuel (e.g. wood, coal, petrol)
  • Batteries
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15
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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16
Q

1.2

A

Conservation and Dissipation of Energy

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17
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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18
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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19
Q

What is waste energy?

A

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

20
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
21
Q

State two equations to calculate efficiency.

A

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

22
Q

How can the efficiency of a system be increased?

A
  1. Reducing waste output (by lubrication, thermal insulation etc.)
  2. Recycling waste output (e.g. recycling thermal waste energy as input energy)
23
Q

State 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.

24
Q

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

A

Lower, meaning less energy transfers through them.

25
Q

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

A
  • The thickness of the walls
  • The thermal conductivity of the walls
26
Q

State three methods of reducing heat loss in a building.

A
  1. Double glazing
  2. Loft and wall insulation
  3. Thicker walls
27
Q

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

A

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

28
Q

How can the efficiency of a radiator be improved? (Higher)

A

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

29
Q

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

A

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

30
Q

1.3

A

National and Global Energy Resources

31
Q

What is a renewable energy source?

A

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

32
Q

Give four examples of renewable energy resources.

A
  1. Wind Energy
  2. Hydro-Electricity
  3. Tidal Energy
  4. Solar Energy
33
Q

Give an example of a non-renewable energy resource.

A

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

34
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
35
Q

State two disadvantages of using renewable energy resource 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
36
Q

Explain the environmental impacts of burning fossil furls.

A
  • Carbon Dioxide contributes to the greenhouse effect, and causes global warming
  • Sulphur Dioxide leads to acid rain, which can damage buildings and crops
37
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
38
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
39
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
40
Q

How does hydroelectric power produces 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
41
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
42
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
43
Q

What are the disadvantages of hydroelectric power?

A
  • The dam may cause flooding
  • It can cost a lot to install the required infrastructure
44
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
45
Q

Give 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)

Physics Paper 1 (4 decks)

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