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Physics Paper 1 > Energy and Energy Resources > Flashcards

Energy and Energy Resources Flashcards

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1
Q

What is the Law of Conservation of Energy?

A

-Energy cannot be created or destroyed, it can only be transferred usefully, stored or dissipated.

-When energy is dissipated, it is converted to less useful forms such as thermal energy and spread out into the surroundings.

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2
Q

What is a system?

A

-A system is an object or group of objects.

-A closed system is one where there is no energy transfer into the system or out of the system.

-The total energy of a closed system is always the same before and after any such transfers.

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3
Q

Describe the energy transfers in a pendulum

A

-At first, the pendulum is not moving. Kinetic energy is zero. Gravitational potential energy is maximum.

-When swinging down, the gravitational potential energy store is being transferred to the kinetic energy store.

-At the centre, the pendulum is moving at its maximum speed. Kinetic energy is maximum but gravitational potential energy is zero.

-When swinging up, the kinetic energy stored is being transferred to the gravitational potential energy store.

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4
Q

Why will the maximum positions of a pendulum reduce for each swing?

A

-There will be friction as the pendulum swings from side to side. There will also be friction between the pendulum and air particles as the pendulum swings through them.

-Because of the effect of friction, some energy will be transferred to thermal energy at the fixed point and in the air.

-Although the total energy of the system will not change (as it is a closed system), the maximum positions of the pendulum to the left and right gradually reduce.

Over time, the pendulum will stop swinging as all of the energy is eventually transferred to thermal (heat) energy.

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5
Q

Describe the energy transfers in a bungee jump

A

-The bungee jumper has not jumped. All of the energy in the system is in the gravitational potential energy store.

-The bungee jumper is falling. The gravitational potential energy store is being transferred to the kinetic energy store.

-The bungee cord is just becoming taut. The energy is a combination of the gravitational potential energy store and the kinetic energy store.

-The bungee cord is stretching. The gravitational potential energy store and the kinetic energy store are transferred to the elastic potential energy store.

-The bungee cord is recoiling. The elastic potential energy store is transferred to the kinetic energy store and the gravitational potential energy store.

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6
Q

Why can the bungee jumper not return to its original hight?

A

-We are assuming that all of the gravitational potential energy of the jumper is transferred to elastic potential energy in the bungee cord.

-However, some energy will be dissipated to thermal energy. For example, as the jumper falls through the air, there will friction between the jumper and air particles.

Secondly, as the bungee cord stretches and shortens again, some of the elastic potential energy is transferred to thermal energy in the bungee cord by heating.

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7
Q

What is work done?

A

-When an object is moved by a force, work is done on the object by the force so the force transfers energy to the object.

-The amount of energy transferred to the object is equal to the work done on it.

-Energy transferred = Work done

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8
Q

What is the equation for work done?

A

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

W=Fs

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9
Q

What is meant by kinetic energy?

A

Kinetic energy stores describes the object has because it is moving.

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10
Q

What is the equation for kinetic energy?

A

Kinetic energy (J) = 0.5 x mass (g) x speed² (m/s)

Ek = (1/2)mv²

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11
Q

What is meant by gravitational potential energy?

A

Gravitational potential energy stores are used to describe the energy stored in an object because of its position, such as an object above the ground.

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12
Q

What is the equation for gravitational potential energy?

A

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

ΔEp = mgh

The gravitational field strength on Earth is 9.8

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13
Q

What is meant by elastic potential energy?

A

Elastic potential energy describes the energy stored in a springy object when it is squashed or stretched.

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14
Q

What is the equation for elastic potential energy?

A

Elastic potential energy (J) = o.5 x spring constant (N/m) x extension²

Ee = (1/2)ke²

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15
Q

What does dissipation mean?

A

The energy that is not usefully transferred and stored in less useful ways.

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16
Q

What is meant by power?

A

Power is the rate at which energy is transferred- how much energy is transferred every second.

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17
Q

What is the equation for power?

A

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

P = E/t

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18
Q

What is input and output power?

A

For any appliance,

-Output power is the useful energy transferred by it per second

-Input power is the energy per second supplied to it

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19
Q

What is the equation for power wasted?

A

Power wasted = Total Power In - Total Power Out

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20
Q

What is meant by efficiency?

A

-The efficiency of an energy transfer tells us what fraction of the energy we put into an appliance is transferred to useful forms of energy.

-We can never get an efficiency greater than 100%. This would mean that we had created energy.

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21
Q

What is the equation for efficiency?

A

Efficiency = useful output energy transfer/ total output energy transfer

For a percentage:
Efficiency = (useful power output/ total power input) x100

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22
Q

Give reasons for why devices waste energy

A

-Friction between the moving parts causes heating

-The resistance of a wire causes it to get hot when a current passes through it

-Air resistance causes a force on a moving object that opposes its motion. Energy transferred from the object to the surroundings by this force is wasted.

-Sound created by machinery causes energy transfer to the surroundings.

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23
Q

Give ways to resolve the problem of wasted energy.

A

-Lubricate moving parts to reduce friction

-In circuits, use wires with as little electrical resistance as possible

-Streamline the shapes of moving objects to reduce air resistance

-Cut out noise (e.g. tighten loose parts to reduce vibration)

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24
Q

Describe how energy is used and wasted in a light bulb

A

Useful energy:
-light emitted from glowing filament

Wasted energy:
-energy transfer from the filament, heating the surroundings

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25
Q

Describe how energy is used and wasted in a hairdryer

A

Useful energy:
-kinetic energy of the air driven by a fan
-energy heating air flowing past the heater filament

Wasted energy:
-sound of fan motor
-energy heating the hairdryer itself

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26
Q

Describe how energy is used and wasted in an electric heater

A

Useful energy:
-energy heating the surroundings

Wasted energy:
-light emitted from the glowing element

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27
Q

Describe what is Meant by Conduction

A

Conduction is the process where vibrating particles transfer energy to neighbouring particles

28
Q

Describe how Energy is Transferred Through a Solid by Heating

A

-Energy transferred to an object by heating is transferred to the thermal energy store of the object. This energy is shared across the kinetic energy stores of the particles in the object.

-The particles is the part of the object being heated vibrate more and collide with each other. These collisions cause energy to be transferred between particles’ kinetic energy stores. This is conduction.

-This process continues throughout the object until the energy is transferred to the other side of the object. It is then usually transferred to the thermal energy store of the surroundings.

29
Q

What is meant by High Thermal Conductivity

A

-Thermal conductivity is a measure of how quickly energy is transferred through a material.

-A high thermal conductivity means that a material transfers (conducts) a large amount of thermal energy through it quickly.

-Insulators have a low thermal conductivity as they do not allow very much thermal energy to transfer through them.

30
Q

Describe what is Meant by Convection

A

-Convection is where energetic particles move away from hotter to cooler regions.

31
Q

Explain what Causes Convection Currents

A

-Convection happens in gases and liquids. Energy is transferred by heating to the thermal energy store of the liquid or gas. This energy is shared across the kinetic energy stores of the particles in the gas or liquid.

-The particles in liquids and gases are able to move. When a region of a liquid or gas is heated, the particles move faster and the space between individual particles increases. This causes the density of the region being heated to decrease.

-Because liquids and gases can flow, the warmer and less dense region will rise above denser, cooler regions. If there is a constant heat source, a convection current can be created.

32
Q

Describe how Radiators Create Convection Currents

A

-Heating a room with a radiator relies on creating convection currents in the air of the room.

-Energy is transferred from the radiator to the nearby air particles by conduction (the air particles collide with the radiator surface).

-The air by the radiator becomes warmer and less dense (as the particles move quicker).

-The warm air rises and is replaced by cooler air. The cooler air is then heated by the radiator. At the same time, previously heated air transfers energy to the surroundings.

-This cycle repeats, causing a flow of air to circulate around the room- this is a convection current.

33
Q

Explain the Advantages of Packing the cavity with Insulating Material in Houses in the UK

A

-In the UK, houses are kept around 20°C (room temperature). The UK has a relatively cool climate.

-For most months of the year, the temperature outside a house will be lower than the temperature inside. This means that thermal energy will tend to transfer from the inside of the house to the outside.

-However, if we pack the wall cavity with an insulating material, then we can significantly reduce the amount of thermal energy that is transferred out of the house.

-This means that less energy will be required to heat our homes and that our heating bills will be reduced

34
Q

Explain how Double Glazing Reduces Thermal Energy Transfer from a House to the Outside.

A

-A single sheet of glass has a relatively high thermal conductivity (5.8). In single-glazing, a significant amount of thermal energy can be transferred from the interior of the house to the outside through the windows.

-However, with double-glazing, we have two sheets of glass with an air gap between them. Air has a much lower thermal conductivity (3.7) compared to glass.

-This means that with double glazing, a much smaller amount of thermal energy is transferred from the interior of the house to the outside.

35
Q

Describe how Loft Insulation Reduces Thermal Energy Transfer through the Roof of a House

A

-Loft insulation has a low thermal conductivity.

-In uninsulated houses, a large amount of thermal
energy passes through the roof.

-However, with loft insulation, the transfer of thermal energy through the roof is significantly reduced.

36
Q

Apart from Insulating Materials, give another way to Reduce the Rate of Thermal Energy Transfer from a House

A

-Another way of reducing thermal energy transfer from a house is to make the walls thick.

-Thicker walls have a lower thermal conductivity than thinner walls.

37
Q

Describe a Method for the Investigating methods of Insulation - Materials Required Practical

A

-Place a small beaker into a larger beaker. Fill the small beaker with hot water from a kettle. Put a piece of cardboard over the beakers as a lid.

-The lid should have a hole suitable for a thermometer. Place a thermometer into the smaller beaker through the hole.

-Record the temperature of the water in the small beaker and start the stopwatch. Record the temperature of the water every 2 minutes for 20 minutes.

-Repeat steps 1-6, each time packing the space between the large beaker and small beaker with the chosen insulating material. Plot a graph of temperature (y-axis) against time (x-axis).

38
Q

Explain the Purpose of the Lid in the Investigating methods of Insulation - Materials Required Practical

A

-The lid reduces thermal energy transfer to the air above the beakers.

-If we allowed thermal energy to escape in this way, it would produce inaccurate results.

39
Q

What does the Investigating methods of Insulation - Materials Required Practical Show

A

-The curve which takes the longest time for the water temperature to drop (the shallowest) should be the material which is the best insulator.

-The temperature falls quickly at high temperatures and slowly at low temperatures.

-When the beaker is at a high temperature, there is a big difference between the temperature of the beaker and the temperature of the surrounding air. This means there is a high rate of transfer.

-When the beaker is at a lower temperature, there is less difference between the temperature of the beaker and the temperature of the surrounding air. This means there is a lower rate of transfer.

40
Q

Describe a Method for the Investigating methods of Insulation - Thickness Required Practical

A

-Wrap a sheet of newspaper around a 100 ml beaker.
Fill the beaker with hot water from a kettle. Put a piece of cardboard over the beaker as a lid. The lid should have a hole suitable for a thermometer.

-Place a thermometer into the beaker through the hole.
Record the temperature of the water in the beaker and start the stopwatch.

Record the temperature of the water every 2 minutes for 20 minutes.

-Repeat steps 1-6, each time adding another layer of newspaper around the beaker until there are 10 layers of newspaper wrapped around the beaker.
Plot graphs of temperature against time.

41
Q

What does the Investigating methods of Insulation - Thickness Required Practical Show

A

-The curve which takes the longest time for the water temperature to drop (the shallowest gradient) shows the amount of layers that provide the best insulation.

-The curve for no insulation has the steepest gradient at any given time interval when compared to any other curve. As the number of layers increases, the gradient of each curve decreases at any given time interval.

-Having more layers of paper increases the insulation which means the temperature drops more slowly. The thickest insulation has the lowest rate of cooling.

-The temperature falls quickly at high temperatures and slowly at low temperatures.

42
Q

What is the Equation for the rate of Cooling

A

Rate of cooling (°C) = change in temperature (°C) / time (minutes)

43
Q

What is Infrared Radiation

A

-Infrared radiation is a type of electromagnetic wave. It can be emitted and absorbed by all objects. The higher the temperature, the more IR an object will emit.

-It is used in TV remotes, thermal imaging cameras and space exploration.

-All bodies, no matter their temperature emit and absorb IR. If the object is at a constant temperature it emits IR at the same rate as it absorbs it.

44
Q

What is Black Body Radiation

A

-A perfect black body is something which absorbs all infrared radiation that hits it. It doesn’t reflect or transmit any radiation. It is also the best possible emitter of radiation.

-Objects at a constant temperature will emit a range of wave lengths of radiation. Some wavelengths will have a different colour.

-As you heat up an object, you can change the wavelengths of radiation emitted. This can change the objects colour.

45
Q

What is Specific Heat Capacity

A

Specific Heat Capacity is the energy needed to change 1kg of an object by 1°C.

46
Q

What is the Equation for Specific Heat Capacity

A

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

47
Q

Describe a Method for the Specific Heat Capacity Required Practical

A

-Place an empty beaker onto a balance and set the balance to zero. pour the liquid into the beaker and record the mass.

-Next, place an immersion heater and thermometer into the liquid. Record the starting temperature of the liquid.

-Wrap the beaker in the insulating foam. Connect the immersion heater to a joulemeter and a power pack.

-Turn on the powerpack and leave the apparatus for around 10-30 minutes (depending on the material). This will give enough time for the temperature of the liquid to increase.

-Read the final temperature on the thermometer and the total number of joules of energy transferred to thermal energy by the immersion heater. Calculate the specific heat capacity.

48
Q

Explain the Function of the Joulemeter in the Specific Heat Capacity Practical

A

-The joulemeter measures the amount of electrical energy transferred from the powerpack to the
immersion heater.

-We can assume that the immersion heater is 100% efficient in transferring electrical energy to thermal energy.

-This means the reading on the joulemeter tells us the number of joules of thermal energy passing into the liquid.

49
Q

List Solutions to Sources of Inaccuracy in the Specific Heat Capacity Practical

A

-Thermal energy passing out of the beaker into the air: Wrap the beaker with an insulator with a low thermal conductivity.

-Not all thermal energy passing into the liquid: Make sure that the immersion heater is fully submerged in the liquid.

-Incorrect reading of the thermometer: Use an electronic temperature probe (or have several people read the thermometer and take a mean of their readings).

-Thermal energy not being spread through the liquid: Stir the liquid.

50
Q

What are the Advantages of using Fossil Fuels as Energy Resources

A

-Fossil fuels are reliable because they are always available to provide energy (unlike renewable energy sources).

-Fossil fuels can also release a very large amount of energy, so can deal with large increases in demand.

-Fossil fuels are also abundant (ie there are large amounts in the world). This also makes them relatively cheap.

-Lastly, fossil fuels are versatile and can be used for transport, heating and generating electricity.

51
Q

What are the Disadvantages of using Fossil Fuels as Energy Resources

A

-Burning fossil fuels releases carbon dioxide into the atmosphere which contributes to climate change.

-Non-renewable resources are resources which are not replenished as they are used.

52
Q

What are the Impacts of Pollutants released by Coal and Diesel

A

Coal releases Sulfur dioxide. This can cause acid rain, damaging buildings and trees.

Diesel releases Nitrogen oxides. These can increases the risk of breathing disorders and heart disease. They can also cause acid rain, damaging buildings and trees.

Both diesel and coal release Carbon particles. These can increases the risk of breathing disorders and heart disease.

53
Q

What are the Advantages of Nuclear Energy

A

-Once a nuclear power plant has been built, generating electricity produces no carbon dioxide. This means that nuclear power does not contribute to climate change.

-A nuclear power plant will always generate a lot of electricity exactly when it is needed. this means that nuclear power is extremely reliable.

54
Q

What are the Disadvantages of Nuclear Energy

A

-Because a nuclear power plant contains radioactive elements, at the end of its life, it must be dismantled. This is called decommissioning and this takes many years and is very expensive.

-Nuclear power plants contain large amounts of highly radioactive elements. these are potentially extremely dangerous if they are ever released e.g. due to an accident or natural disaster.

-Nuclear power plants generate radioactive waste. This is highly dangerous and must be safely stored for many thousands of years before it is safe.

55
Q

Why did Burning Coal Generate most Electricity and Heating in the UK in the 1950s

A

-The UK did not have to import coal as the UK has large coal deposits.

-In the 1950s scientists did not know about climate change.

56
Q

Why has the use of Coal to Generate Electricity Dropped since the 1950s

A

-In the 1950s, nuclear power was developed. The UK began to build nuclear power plants to generate
electricity. Today, around 20% of the UK’s electricity comes from nuclear power.

-In the 1970s, the UK discovered large oil and gas deposits in the North Sea and started using these to
generate electricity and for heating.

57
Q

Compare Burning Coal to Burning gas to Generate Electricity

A

-Generating electricity by burning gas generates less carbon dioxide than burning coal.

-This means that burning gas contributes less to climate change.

-Gas-fired power stations can also be switched
on very rapidly when demand for electricity is high.

-This is called a short start-up time. Coal power
stations have a very long start-up time.

58
Q

How have Economic Factors Caused Non-renewable Energy Sources to still be Heavily used in the UK

A

-Economic factors are linked to cost.

-It would be possible for the UK to completely phase out fossil fuels if the country converted all energy use to electricity and built a lot of nuclear power stations and expanded renewable energy generation.

-However, the cost of that would be extremely high.

-Also, a lot of people currently employed in the fossil-fuel industry (eg oil) could lose their jobs.

59
Q

Advantages of all Renewable Energy Resources

A

-They will never run out.

-They do not release carbon dioxide.

60
Q

Evaluate the use of Wind Power to Generate Electricity

A

-Electricity is generated by wind driving the blades on a wind turbine around to turn a generator.

-It has low running costs and creates no pollution.

-It is unreliable. A turbine requires a certain wind speed to generate electricity. We sometimes experience periods with very low wind speeds. If this happens, electricity output from wind farms falls. This means we cannot rely on wind power for all of our electricity.

-Takes up large areas that could be used for farming and some people say windmills spoil the view.

61
Q

Evaluate the use of Solar Power to Generate Electricity

A

-Solar cells are flat, solid cells and use the suns energy to generate electricity. Solar heating panels use the suns heat to heat water directly.

-Solar power creates no pollution and and its environmental impact is very low.

-It is unreliable. Solar power works best in sunny conditions. Cloudy weather reduces the electricity output of solar panels. And of course, solar panels cannot generate electricity at night.

-Lots of cells are needed to generate enough power to be useful. This can also be expensive.

62
Q

Evaluate the use of Hydroelectric Power to Generate Electricity

A

-To generate electricity, generators are turned by wate running down a hill.

-It is generally very reliable (unless there is a significant
drought). This means we can rely on hydroelectric power to generate electricity exactly when we need it.

-Habitats are destroyed when dams are built. Building a dam is extremely harmful to habitats of animals and plants. As the land behind the dam floods, this also destroys a huge amount of habitat.

-For hydroelectricity, a country requires a large number of fast flowing rivers, or places where a river can be dammed and a valley can be flooded (creating a huge lake). In the UK, we simply do not have these possibilities.

63
Q

Evaluate the use of Tidal, Wave and Geothermal Power to Generate Electricity

A

-Tidal and wave generate electricity by turning a floating generator.

-Geothermal comes from the energy transferred by radioactive substances deep inside the Earth.

-They are all reliable. For example, the tide comes in and goes out twice every day and we can rely on it to generate electricity. The coast around the UK provides plenty of opportunity to capture the energy in waves.

-Geothermal energy relies on the heat present in underground rocks. It is not used extensively in the UK but it is used in other countries such as Iceland.

-However, all of these methods are expensive.

64
Q

What are the Advantages of Biofuels

A

-Biofuels are carbon neutral. To produce biofuels, we grow plants. As they grow, they take in carbon dioxide by photosynthesis. We then convert the plants to biofuel (e.g. biodiesel).

-Burning biofuels releases carbon dioxide. This does not release more carbon dioxide than originally absorbed from the atmosphere.

-This means burning biofuels releases no net carbon dioxide.

65
Q

What are the Disadvantages of Biofuels

A

-Strictly speaking biofuels are not 100% carbon neutral. That is because it requires energy to grow the plants (eg in making fertilisers) and transporting them to the biofuel factory.

-It also requires energy to make the biofuel. If all of this energy is generated by burning fossil fuels, then that will release some carbon dioxide to the atmosphere

-To make biofuels, you need to grow plants. If we were to replace fossil fuels with biofuels, then we would need to grow a vast amount of plants.

-This would require a lot of farmland. Since this farmland would not be used to grow food, this could push up food prices.

66
Q

How Is Energy Transported to the Home

A

-A boiler heats the energy resource

-This turns to steam which moves a turbine

-The turbine turns a generator which creates electricity

-The electricity is sent to the national grid

-A system of pylons and cables transports the electricity to the home

Physics Paper 1 (4 decks)

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