https://filestore.aqa.org.uk/resources/physics/specifications/AQA-8463-SP-2016.PDF
Conservation & dissipation of energy (P1)
Energy Stores
● Energy can be stored in different forms and can be transferred by heating, waves,
electrical current, or when a force moves an object.
● Examples of energy stores: chemical, thermal, kinetic, mechanical, gravitational potential
● Law of conservation of energy: energy can not be created or destroyed (it can only be
transferred from one store to another)
● Within a closed system, the total energy of a system is constant.
Energy and Work
● Energy transferred = work done
● Work done to overcome friction is transferred as energy to the thermal energy stores of
the objects that rub together and to the surroundings.
Gravitational potential energy store
● g . p . e . = mass × gravitational field strength × height [Ep = m g h]
● When an object moves upwards, the energy in its gravitational potential energy store
increases and is equal to the work done by the gravitational force equal to it. And vice
versa when an object moves downwards.
● The work done depends on: its change in height and weight
● NOTE: If a ball is thrown up, on the way up, energy is transferred from its kinetic energy
store to the gravitational potential energy store and it moves up. Then when it reaches its
maximum height, GPE is at its highest and Ek is 0. Then as it begins to fall down, the
energy gets transferred from its gravitational potential energy store to the kinetic energy
store until it reaches the ground and has 0 GPE and Ek.
Kinetic Energy
1
● kinetic energy = 0.5 × mass × speed 2 [Ek = 2
m v2]
● Calculates the energy of a moving object
Elastic Potential Energy
1
● elastic potential energy = 0.5 × spring constant × extension2 [Ee = 2
k e2]
● This is only the case for hooke’s law when F = ke where the k is the spring constant.
Energy Dissipation
● Useful energy - the energy transferred to where it is supposed to go
● Wasted energy - the energy that is not usefully transferred
● Wasted energy is dissipated to the surroundings, e.g when there is fiction thermal
energy is transferred to the surroundings
● Energy becomes less useful the more it is spread out
,Efficiency
𝑢𝑠𝑒𝑓𝑢𝑙 𝑝𝑜𝑤𝑒𝑟 𝑜𝑢𝑡𝑝𝑢𝑡
● efficiency = 𝑡𝑜𝑡𝑎𝑙 𝑝𝑜𝑤𝑒𝑟 𝑖𝑛𝑝𝑢𝑡
● Improving efficiency:
○ Lubrication can be used to reduce friction which results in heating
○ Use wires with as little electrical resistance to prevent the wire getting hot when a
current passes through it
○ Streamline the shaped of moving objects to reduce air resistance
○ Cut out noise to reduce Energy transferred to the surroundings by sound energy
Power
● Power is the rate of energy transfer
𝑤𝑜𝑟𝑘 𝑑𝑜𝑛𝑒 / 𝑒𝑛𝑒𝑟𝑔𝑦 𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟𝑟𝑒𝑑
● power = 𝑡𝑖𝑚𝑒
Energy transfer by heating (P2)
Energy transfer by conduction
● The greater the thermal conductivity of a material the more energy per second transfers
by conduction
● Good insulators are materials that have low thermal conductivity so energy transfer
through them is as low as possible
● The effectiveness of the insulating material depends on:
○ The temperature difference across the material
○ The thickness of the material (increasing thickness, improves insulation)
○ The thermal conductivity of the material
RPA 1: Testing sheets of materials as insulators
● Use different materials to insulate identical cans of hot water
● When choosing your materials consider which properties will make the materials good
thermal insulators for example the thickness of a material or the colour of the material
● Control Variables:
○ The volume of water
○ Its temperature at the start needs to be the same
● Dependant variable: Change in temperature
● Independent variable: Material of insulator
● Use the thermometer to measure the water temperature after a fixed time and then use
your results to work out which is the best insulator
Infrared Radiation
● A part of the electromagnetic spectrum
● All objects emit and absorb infrared radiation
● The higher the Temperature of an object, the more infrared radiation it emits at a given
time
, ● Blackbody radiation is radiation emitted by a body that serves all the radiation incident
on it
● A light shiny outer surface emits a lot less radiation than dark, matt surfaces.
● In the Earth's atmosphere infrared radiation is reflected back into space or absorbed by
the Earth's atmosphere or by the earth's surface; emitted from the Earth's surface or
from the Earth's atmosphere into space
● CO2 molecules absorbed and re-emitted infrared radiation back into the ground
Specific heat capacity
● Specific heat capacity is the energy required to change 1kg of a substance by 1 degrees
celsius.
● change in thermal energy = mass × specific heat capacity × temperature change
[∆ E = m c ∆ θ ]
Heating and Insulating buildings
● Heaters can be gas or electric
● Central heating systems can be oil or gas
● When your home heating system is transferring energy into your home, it is also
transferring energy to the surroundings outside of your home
● To minimise this loss of energy we use: loft insulation, cavity wall insulation,
double-glazed windows (and doors), thicker bricks with lower thermal conductivity.
● Loft insulation reduces the rate of energy transfer through the roof. The air between the
fibres of fibreglass also helps to reduce the rate of energy transfer by conduction.
● Cavity wall insulation reduces the rate of energy transfer through the walls. The cavity
(the space between the two layers of brick that make a wall) is pumped with insulation. It
traps air in small pockets reducing the rate of energy transfer by conduction
● Aluminium foil between a radiator panel and the wall reflects radiation away from the wall
and so reduces the rate of energy transfer by radiation
● Double glazed windows have 2 glass panes with dry air (or a vacuum) between the
panes. The thicker the glass and lower its thermal conductivity is, the slower the rate of
energy transfer through it by conduction
● Dry air is a good insulator so it reduces the rate of energy transfer by convection.
● If the external walls of a warm building have thicker bricks and lower thermal
conductivity, the rate of transfer of energy will be lower.
● Solar panels absorb infrared radiation from the sun and use it to generate electricity
directly or to heat water directly.
Energy Resources (P3)
Energy Demand
● Most of the energy we use comes from burning fossil fuels, mostly gas/oil/coal.
● The energy supplied to homes, offices and factories is mostly supplied by gas or
generated in coal or gas-fired power stations
● Oil is needed to fuel vehicles of all sorts, including aeroplanes and ships.
, ● (crosses with chemistry) Fossil fuels are extracted from underground or under the sea
bed and then are transported to oil refineries and power stations. Fossil fuels are long
dead animals and plants (plankton etc.)
● Energy is generated from these sources in a power station by burning the fuel which
heats water. The water then evaporates to produce steam. The steam drives a turbine
which then drives an electrical generator.
Biofuel
● Biofuel is any fuel taken from living or recently living organisms.
● Methane gas, a type of biofuel, can be collected from cows or animal manure, from
sewage works, decaying rubbish and other sources.
● Wasted vegetable oil and plants, straw, woodchip and nutshells are also all examples of
biofuel
● Advantages of Biofuel
+ renewable - its biological source either regrows (vegetation) or is continually
produced (sewage and rubbish)
+ Carbon-neutral - the carbon that the living organism takes in from the
atmosphere whilst alive can balance the amount that is released when biofuel is
burnt.
● Disadvantages of Biofuel
- Can lead to food shortages
- Uses up a lot of land, destroying local habitats
Nuclear Power
● Uranium or plutonium rods are used in the reactor as they have unstable nuclei which
split into 2 and energy is transferred from the nucleus when this happens. This energy
heats water to produce steam and this steam then drives a turbine which drives an
electrical generator to produce electricity. Alternatively, the energy produced by the
uranium can get passed through a pipe to a heat exchanger then back to the reactor
core?
● Advantages of nuclear power
+ Around x10,000 more energy is released per kg of a fossil fuel
+ No greenhouse gases produced
+ Reliable
● Disadvantages of nuclear power
- Radioactive waste is produced and it needs to be stored underground for many
years until it is no longer radioactive
- If the radioactive waste escapes it is hazardous to the environment and life.
Wind Turbines
● The mechanical energy that turns the blades of a wind turbine gets converted into
electricity by a turning electric generator.
● As wind speed increases, power generated increases
● Advantages of wind turbines
+ Take up small plots of land
+ Never run out
Conservation & dissipation of energy (P1)
Energy Stores
● Energy can be stored in different forms and can be transferred by heating, waves,
electrical current, or when a force moves an object.
● Examples of energy stores: chemical, thermal, kinetic, mechanical, gravitational potential
● Law of conservation of energy: energy can not be created or destroyed (it can only be
transferred from one store to another)
● Within a closed system, the total energy of a system is constant.
Energy and Work
● Energy transferred = work done
● Work done to overcome friction is transferred as energy to the thermal energy stores of
the objects that rub together and to the surroundings.
Gravitational potential energy store
● g . p . e . = mass × gravitational field strength × height [Ep = m g h]
● When an object moves upwards, the energy in its gravitational potential energy store
increases and is equal to the work done by the gravitational force equal to it. And vice
versa when an object moves downwards.
● The work done depends on: its change in height and weight
● NOTE: If a ball is thrown up, on the way up, energy is transferred from its kinetic energy
store to the gravitational potential energy store and it moves up. Then when it reaches its
maximum height, GPE is at its highest and Ek is 0. Then as it begins to fall down, the
energy gets transferred from its gravitational potential energy store to the kinetic energy
store until it reaches the ground and has 0 GPE and Ek.
Kinetic Energy
1
● kinetic energy = 0.5 × mass × speed 2 [Ek = 2
m v2]
● Calculates the energy of a moving object
Elastic Potential Energy
1
● elastic potential energy = 0.5 × spring constant × extension2 [Ee = 2
k e2]
● This is only the case for hooke’s law when F = ke where the k is the spring constant.
Energy Dissipation
● Useful energy - the energy transferred to where it is supposed to go
● Wasted energy - the energy that is not usefully transferred
● Wasted energy is dissipated to the surroundings, e.g when there is fiction thermal
energy is transferred to the surroundings
● Energy becomes less useful the more it is spread out
,Efficiency
𝑢𝑠𝑒𝑓𝑢𝑙 𝑝𝑜𝑤𝑒𝑟 𝑜𝑢𝑡𝑝𝑢𝑡
● efficiency = 𝑡𝑜𝑡𝑎𝑙 𝑝𝑜𝑤𝑒𝑟 𝑖𝑛𝑝𝑢𝑡
● Improving efficiency:
○ Lubrication can be used to reduce friction which results in heating
○ Use wires with as little electrical resistance to prevent the wire getting hot when a
current passes through it
○ Streamline the shaped of moving objects to reduce air resistance
○ Cut out noise to reduce Energy transferred to the surroundings by sound energy
Power
● Power is the rate of energy transfer
𝑤𝑜𝑟𝑘 𝑑𝑜𝑛𝑒 / 𝑒𝑛𝑒𝑟𝑔𝑦 𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟𝑟𝑒𝑑
● power = 𝑡𝑖𝑚𝑒
Energy transfer by heating (P2)
Energy transfer by conduction
● The greater the thermal conductivity of a material the more energy per second transfers
by conduction
● Good insulators are materials that have low thermal conductivity so energy transfer
through them is as low as possible
● The effectiveness of the insulating material depends on:
○ The temperature difference across the material
○ The thickness of the material (increasing thickness, improves insulation)
○ The thermal conductivity of the material
RPA 1: Testing sheets of materials as insulators
● Use different materials to insulate identical cans of hot water
● When choosing your materials consider which properties will make the materials good
thermal insulators for example the thickness of a material or the colour of the material
● Control Variables:
○ The volume of water
○ Its temperature at the start needs to be the same
● Dependant variable: Change in temperature
● Independent variable: Material of insulator
● Use the thermometer to measure the water temperature after a fixed time and then use
your results to work out which is the best insulator
Infrared Radiation
● A part of the electromagnetic spectrum
● All objects emit and absorb infrared radiation
● The higher the Temperature of an object, the more infrared radiation it emits at a given
time
, ● Blackbody radiation is radiation emitted by a body that serves all the radiation incident
on it
● A light shiny outer surface emits a lot less radiation than dark, matt surfaces.
● In the Earth's atmosphere infrared radiation is reflected back into space or absorbed by
the Earth's atmosphere or by the earth's surface; emitted from the Earth's surface or
from the Earth's atmosphere into space
● CO2 molecules absorbed and re-emitted infrared radiation back into the ground
Specific heat capacity
● Specific heat capacity is the energy required to change 1kg of a substance by 1 degrees
celsius.
● change in thermal energy = mass × specific heat capacity × temperature change
[∆ E = m c ∆ θ ]
Heating and Insulating buildings
● Heaters can be gas or electric
● Central heating systems can be oil or gas
● When your home heating system is transferring energy into your home, it is also
transferring energy to the surroundings outside of your home
● To minimise this loss of energy we use: loft insulation, cavity wall insulation,
double-glazed windows (and doors), thicker bricks with lower thermal conductivity.
● Loft insulation reduces the rate of energy transfer through the roof. The air between the
fibres of fibreglass also helps to reduce the rate of energy transfer by conduction.
● Cavity wall insulation reduces the rate of energy transfer through the walls. The cavity
(the space between the two layers of brick that make a wall) is pumped with insulation. It
traps air in small pockets reducing the rate of energy transfer by conduction
● Aluminium foil between a radiator panel and the wall reflects radiation away from the wall
and so reduces the rate of energy transfer by radiation
● Double glazed windows have 2 glass panes with dry air (or a vacuum) between the
panes. The thicker the glass and lower its thermal conductivity is, the slower the rate of
energy transfer through it by conduction
● Dry air is a good insulator so it reduces the rate of energy transfer by convection.
● If the external walls of a warm building have thicker bricks and lower thermal
conductivity, the rate of transfer of energy will be lower.
● Solar panels absorb infrared radiation from the sun and use it to generate electricity
directly or to heat water directly.
Energy Resources (P3)
Energy Demand
● Most of the energy we use comes from burning fossil fuels, mostly gas/oil/coal.
● The energy supplied to homes, offices and factories is mostly supplied by gas or
generated in coal or gas-fired power stations
● Oil is needed to fuel vehicles of all sorts, including aeroplanes and ships.
, ● (crosses with chemistry) Fossil fuels are extracted from underground or under the sea
bed and then are transported to oil refineries and power stations. Fossil fuels are long
dead animals and plants (plankton etc.)
● Energy is generated from these sources in a power station by burning the fuel which
heats water. The water then evaporates to produce steam. The steam drives a turbine
which then drives an electrical generator.
Biofuel
● Biofuel is any fuel taken from living or recently living organisms.
● Methane gas, a type of biofuel, can be collected from cows or animal manure, from
sewage works, decaying rubbish and other sources.
● Wasted vegetable oil and plants, straw, woodchip and nutshells are also all examples of
biofuel
● Advantages of Biofuel
+ renewable - its biological source either regrows (vegetation) or is continually
produced (sewage and rubbish)
+ Carbon-neutral - the carbon that the living organism takes in from the
atmosphere whilst alive can balance the amount that is released when biofuel is
burnt.
● Disadvantages of Biofuel
- Can lead to food shortages
- Uses up a lot of land, destroying local habitats
Nuclear Power
● Uranium or plutonium rods are used in the reactor as they have unstable nuclei which
split into 2 and energy is transferred from the nucleus when this happens. This energy
heats water to produce steam and this steam then drives a turbine which drives an
electrical generator to produce electricity. Alternatively, the energy produced by the
uranium can get passed through a pipe to a heat exchanger then back to the reactor
core?
● Advantages of nuclear power
+ Around x10,000 more energy is released per kg of a fossil fuel
+ No greenhouse gases produced
+ Reliable
● Disadvantages of nuclear power
- Radioactive waste is produced and it needs to be stored underground for many
years until it is no longer radioactive
- If the radioactive waste escapes it is hazardous to the environment and life.
Wind Turbines
● The mechanical energy that turns the blades of a wind turbine gets converted into
electricity by a turning electric generator.
● As wind speed increases, power generated increases
● Advantages of wind turbines
+ Take up small plots of land
+ Never run out
