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P1 Flashcards

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1
Q

Define a system

A

An object or group of objects.

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2
Q

What happens when a system changes?

A
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3
Q

6 examples of energy stores

A

Thermal energy, kinetic energy, gravitation potential energy, elastic potential energy, chemical energy, nuclear energy

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4
Q

How many joules is 1 kJ?

A

1kJ is 1000J

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5
Q

Define work done

A

Work is done whenever energy is transferred from one store to another.

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6
Q

2 types of work

A

Mechanical work and electrical work

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7
Q

Define mechanical work

A

Mechanical work is using force to move an object.

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8
Q

Define electrical work

A

Electrical work is a current transferring energy.

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9
Q

How to calculate work done?

A

Work done (J) = Force (N) x Distance (m)

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10
Q

Changes involved in the way energy is stored when an object is projected upwards

A

Initial force does work, energy transfer from the chemical energy store (e.g. of the arm) to the kinetic energy of the object and (e.g. arm).

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11
Q

Changes involved in the way energy is stored when a moving object hitting an obstacle

A

Normal contact force does work, energy transfer from the kinetic energy store (e.g. of the car) to other energy stores such as elastic potential and thermal energy stores of the obstacle. Some energy might also be transferred away by sound waves.

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12
Q

Changes involved in the way energy is stored when an object accelerated by a constant force

A

Energy transfer from (e.g. gravitational potential energy when a ball drops) to kinetic energy store.

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13
Q

Changes involved in the way energy is stored when a vehicle slowing down

A

Friction between a car’s brakes and its wheels does work, energy transfer from the kinetic energy store of the wheels to the thermal energy store of the surroundings.

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14
Q

Changes involved in the way energy is stored when water is boiled in an electric heater

A

Electrical energy transfer from the heating system to the thermal energy store of the water.

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15
Q

Define kinetic energy

A

Kinetic energy is energy stored in moving objects.

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16
Q

How to calculate kinetic energy?

A

Kinetic energy = 0.5 x mass x (speed)2

Ek (J) = 1/2 m (kg) v2 (m/s)

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17
Q

Define elastic potential energy

A

Elastic potential energy is the energy stored in a stretched spring.

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18
Q

What is the extension in elastic potential energy?

A

The extension is the spring’s stretch which causes the spring to stretch.

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19
Q

Describe the extension’s proportion to the force applied

A

The extension is directly proportional to the force applied.
If we apply to a greater force, then the extension is no longer directly proportional to the force. At this point, the spring has been stretched beyond the limit of proportionality so it will not return back to its original length if we take away the force.

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20
Q

Define gravitational potential energy

A

Gravitational potential energy is the energy stored in an object due to its position above the Earth’s surface. This is due to the force of gravity acting on an object.

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21
Q

How to calculate gravitational potential energy?

A

Gravitational potential energy = mass x gravitational field strength x height
Ep (J) = m (kg) g (N/kg) h (m)

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22
Q

Define thermal energy

A

Thermal energy is the energy stored due to an object’s temperature.

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23
Q

Define the specific heat capacity of a substance

A

The specific heat capacity of a substance is the amount of energy required to raise the temperature of 1 kg of the substance by 1°C.

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24
Q

9 steps to determine the specific heat capacity of vegetable oil

A
  1. Place a beaker on a balance and press zero.
  2. Add the oil to the beaker and record the mass of the oil.
  3. Place a thermometer and an immersion heater into the oil.
  4. Read the starting temperature of the oil.
  5. Wrap the beaker in insulating foam to reduce thermal energy transfer to the surroundings.
  6. Connect a joulemeter and a powerpack to the immersion heater - tells us how many joules of electrical energy passes into the immersion heater.
  7. Leave for 30 minutes - allow the temperature to rise enough so that we can accurately read it on the thermometer.
  8. Read the number of joules of energy that passed into the immersion heater and final temperature of the oil.
  9. Calculate the specific heat capacity by using the change in thermal energy equation (rearrange it).
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25
Q

4 sources of inaccuracy in the practical

A
  • Thermal energy passing out of the beaker - use an insulator with a lower thermal conductivity.
  • Not all thermal energy passing into the oil - ensure that immersion heater is fully submerged.
  • Incorrect reading of thermometer - use an electronic temperature probe.
  • Thermal energy not spread through the oil - stir the oil.
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26
Q

Define power

A

Power is the rate at which energy is transferred or the rate at which work is done.

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27
Q

2 ways to calculate power

A

• Power = energy transferred / time
P (W) = E (J) /t (s)
• Power = work done / time
P (W) = W (J) /t (s)

28
Q

What is the power of 1 watt equal to?

A

A power of 1 watt is equal to an energy transfer of 1 joules per second.

29
Q

What is the law of conservation of energy?

A

Energy can be tranfserred usefully, stored or dissipated, but cannot be created or destroyed.

30
Q

Define a closed system and give 2 examples

A

No energy can enter or leave, e.g. a pendulum and bungee jump.

31
Q

What causes energy to be transferred to thermal energy?

A

Friction causes energy to be transferred to thermal energy.

32
Q

3 ways to reduce unwanted energy transfers

A

Reducing friction:
• Use a lubricant (e.g. oil) on the fixed point
• Remove the air particles around the system
•Thermal insulation

33
Q

How does thermal conductivity affect the rate of energy transfer?

A

The higher the thermal conductivity of a material the higher the rate of energy transfer by conduction.

34
Q

2 ways to calculate energy efficiency

A
  • Efficiency = useful output energy transfer / total input energy transfer
  • Efficiency = useful power output / total power input
35
Q

2 ways to increase efficiency

A

Increase efficiency by lubrication and thermal insulation

36
Q

How does lubrication increase energy efficiency?

A

Lubrication increases energy efficiency by reducing frictional forces between the objects’ surfaces when they move.

37
Q

How does thermal insulation increase energy efficiency?

A

Insulation increases energy efficiency by reducing the rate of thermal energy tranfer by using material with low thermal conductivity.

38
Q

Define renewable energy resource

A

A renewable energy resource is one that is being replenished or can be replenished as it is used.

39
Q

Define non-renewable energy resource

A

A non-renewable energy resource is one that is not being replenished as it is used.

40
Q

2 non-renewable energy resources

A

Fossil fuels (coal, oil, gas), nuclear fuel

41
Q

3 uses of energy resources

A

Transport, electricity generation, heating

42
Q

4 advantages of fossil fuels

A
  • Reliable - always provide energy when we need it.
  • Release a great deal of energy.
  • Abundant (plentiful) and relatively cheap.
  • Extremely versatile (able to adapt to many functions).
43
Q

2 disadvantages of fossil fuels

A
  • Burning them releases a huge amount of carbon dioxide - contributes to climate change.
  • Release other pollutants - diesel releases carbon particles and nitrogen oxides and coal releases sulfur dioxide which leads to acid rain.
44
Q

2 advantages of nuclear power

A
  • Releases no carbon dioxide - does not contribute to climate change.
  • Reliable - generates a lot of electricity when needed.
45
Q

3 disadvantages of nuclear power

A
  • Contains highly dangerous radioactive materials - materials could be released into the environment if there is an accident.
  • Decommissioning the power plant takes many years and is expensive.
  • Generates large amounts of highly dangerous radioactive waste - must be stored for thousands of years before it is safe.
46
Q

3 advantages of wind power

A
  • Do not add any carbon dioxide to the atmosphere - does not contribute to climate change.
  • No fuel costs and minimal running costs.
  • No permanent damage to the landscape.
47
Q

5 disadvantages of wind power

A
  • Big effect on scenery and spoil the view.
  • Very noisy - disrupt residents.
  • Cannot increase power output when there is extra demand.
  • Initial costs are high.
  • Unreliable when there is no wind.
48
Q

3 advantages of solar power

A
  • Do not add any carbon dioxide to the atmosphere - does not contribute to climate change.
  • Reliable source in sunny countries in the daytime.
  • No running costs.
49
Q

4 disadvantages of solar power

A
  • Use a lot of energy to manufacture.
  • Cannot increase power output when there is extra demand.
  • Initial costs are high.
  • Does not release a great deal of energy.
50
Q

4 advantages of geothermal power

A
  • Do not add any carbon dioxide to the atmosphere - does not contribute to climate change.
  • Reliable - can run continuously.
  • Very little damage to the environment.
  • Can generate electricity or heat buildings directly.
51
Q

2 disadvantages of geothermal power

A
  • Not many suitable locations for power plants.

* High cost of a power plant.

52
Q

4 advantages of hydroelectricity

A
  • Do not add any carbon dioxide to the atmosphere - does not contribute to climate change.
  • Reliable - generates a lot of electricity when needed.
  • No fuel costs and minimal running costs.
  • Useful to generate energy on a small scale in remote areas.
53
Q

A disadvantage of hydroelectricity

A

• Negative impact on the environment due to the flooding of the valley - rotting vegetation releases methane and CO2 and loss of habitats.

54
Q

2 advantages of wave power

A
  • Do not add any carbon dioxide to the atmosphere - does not contribute to climate change.
  • No fuel costs and minimal running costs.
55
Q

6 disadvantages of wave power

A
  • Unreliable - no waves when the wind drops.
  • Initial costs are high.
  • Cannot provide energy on a large scale.
  • Disturbs seabed.
  • Spoils the view.
  • Hazard to boats.
56
Q

2 advantages of energy from tides

A
  • Do not add any carbon dioxide to the atmosphere - does not contribute to climate change.
  • No fuel costs and minimal running costs.
57
Q

5 disadvantages of energy from tides

A
  • Preventing free access by boats.
  • Spoils the view.
  • Alters the habitat of wildlife.
  • Initial costs are high.
  • Unreliable - the height of tide is variable.
58
Q

An advantage of bio-fuels

A

• Fairly reliable - different crops can be grown all year round.

59
Q

3 disadvantages of bio-fuels

A
  • Cannot respond to immediate energy demands.
  • Deforestation for bio-fuels - loss of habitats.
  • Burning of the vegetation increases CO2 and methane emissions.
60
Q

Up until the 1950s, how was electricity generated in the UK and what was used for heating and cooking?

A

Almost all of the electricity generated came from burning coal. Coal and coal gas were used for almost all of heating and cooking.

61
Q

What happened in the 1950s?

A

In the 1950s, nuclear power came online and by the 1980s this produced around 20% of all the UK’s electricity.

62
Q

What happened by 2000?

A

By 2000, as much electricity was generated from burning gas as from coal.

63
Q

2 reasons why the UK switched to gas from coal?

A
  • Burning gas generates less carbon dioxide than burning coal. This contributes less to climate change.
  • Gas-fired power stations are flexible - switched on quickly during periods of high demand (short start-up time).
64
Q

Why did the UK switch to renewables?

A

In the 1970s, scientists began to realise that carbon dioxide emissions from human activity could lead to climate change. At the time, politicians did not really see that as a big issue.
Economic factor - energy from fossil fuels was very cheap. Switching away from it costs money and that could cost jobs.
In 2005, the Kyoto protocol committed countries to reducing greenhouse gas emissions.

65
Q

What may be the future of UK energy?

A

Nuclear power is ideal for a baseload as it cannot be easily turned on or off and does not generate any greenhouse gases.
Emergency power in times of peak demand - gas-fired power stations. This is ideal as the start-up time is very short.
Renewables will provide the bulk of electricity, with nuclear providing a base-load and then gas providing electricity during periods of peak demand.

Physics (4 decks)

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