1. 8.1 Describe the changes involved in the way energy is stored when systems change: There are changes in
the way energy is stored when a system changes. For example: an object projected upwards - The object's energy is slowly
transferred from the kinetic store to the gravitational potential store as it slows down and climbs higher.
2. 8.2 Draw and interpret diagrams to represent energy transfers: .Transfer diagrams
In transfer diagrams the boxes show the energy stores and the arrows show the energy transfers
.Sankey diagrams
Sankey diagrams start off as one arrow that splits into two or more points. This shows how all of the energy in a system is
transferred into different stores.
3. 8.3 In a closed system what happens to the total energy of that system when there are energy
transfers?: where there are energy transfers in a closed system there is no net change to the total energy in that system
4. 8.4 Identify the different ways that the energy of a system can be changed: a) through work done by forces b)
in electrical equipment
c) in heating
5. Energy is transferred by one of the following four types of energy pathway:: .mechanical work - a force moving an
object through a distance
.electrical work - charges moving due to a potential difference
.heating - due to temperature difference caused electrically or by chemical reaction .radiation - energy transferred as a wave eg
light, infrared, sound - the Sun emits light radiation and infrared radiation
6. Describe how heating can change the energy of a system: Heating changes the energy stored within a system by
increasing the energy of the particles that make up that system
This either raises the system's temperature or, produces a change of state (eg. solid to liquid)
An example of the energy change by heating is electrical energy to thermal energy
7. Describe how work done by forces can change the energy of a system: -
When Work is Done against frictional forces, energy is transferred, increasing the temperature of the moving object and the
contact surface. When a force is used to move an object, energy is transferred (because the object has moved) and we say that
Work is Done
An example of the energy change by work done by forces is kinetic energy to thermal energy
8. Describe an example of how work done in electrical equipment can change the energy of a system: An
example of the energy change by work done when a current flow is chemical energy to electrical energy to thermal energy
(Chemical energy from the battery is converted to electrical energy in the components and then transferred to heat in wires)
9. 8.5 Describe how to measure the work done by a force: .Find the direction of the force vector and the direction of
motion
.Find the displacement of your object
.Find the force on the object
.Multiply Force × Distance
.Label your answer in joules
, .work done(J) = force(N) x distance moved in the direction of the force (m)
10. 8.5 Energy transferred (joule, J) is equal to...: work done (joule, J)
11. 8.7 Describe and calculate the changes in energy involved when a system is changed by work done by
forces (give an example): Bringing water to a boil in an electric kettle
Electricity through the element of the kettle increases its internal (thermal) energy which increases the internal (thermal) energy
of the water which increases the temperature of the water
(to calculate this select the right equation from the equation sheet)
12. 8.10 Explain, using examples, how in all system changes energy is dissipated so that it is stored in less
useful ways: No system is perfect. Whenever there is a change in a system, energy is transferred and some of that energy is
dissipated.
Dissipation is a term that is often used to describe ways in which energy is wasted. Any energy that is not transferred to useful
energy stores is said to be wasted because it is transferred to the surroundings.
For example - for a radio or set of speakers the electrical work is transferred into useful sound waves and thermal energy is
dissipated causing a rise in the internal energy store (temperature) of the surroundings
13. 8.11 Mechanical processes become wasteful when...: cause a rise in temperature so dissipating energy in heating
them surroundings
14. 8.12 Define power (and have an exmaple): The rate at which energy is transferred
(An example that illustrates the definition of power is by comparing two electric motors if:
They lift the same weight
They are lifted by the same height
One lifts it faster than the other
The motor that lifts the weight faster is said to have more power
This is because the work done does not depend on time, only the force (weight) and the distance lifted)
15. 8.14 Recall that one watt is equal to...: one joule per second ( J/s) 16. 9.10 Explain ways of reducing
unwanted energy transfer through lubrication: Reducing the friction between two surfaces can reduce this unwanted
energy transfer. Friction is sometimes reduced by placing rollers or ball bearings between the surfaces but, most often, oil is
used to lubricate the surfaces and allow them to slide smoothly over each other.
17. 10.1 Describe the structure of the atom, limited to the position, mass and charge of protons, neutrons and
electrons: The nucleus contains: Protons - positively charged particles with a relative atomic mass of one unit
Neutrons - no charge, and also with a relative atomic mass of one unit
Almost all of the atom is empty space, but moving around the nucleus there are: Electrons - negative charge with almost no mass
(1/2000 the mass of a proton or neutron)
18. 10.3 Describe the differences between series and parallel circuits: In series circuits, the different components are
connected in a line, end to end, between the positive and negative of the power supply. In parallel circuits, each component
is separately connected to the positive and negative of the supply.
-In a series circuit, the current is the same at all points
the way energy is stored when a system changes. For example: an object projected upwards - The object's energy is slowly
transferred from the kinetic store to the gravitational potential store as it slows down and climbs higher.
2. 8.2 Draw and interpret diagrams to represent energy transfers: .Transfer diagrams
In transfer diagrams the boxes show the energy stores and the arrows show the energy transfers
.Sankey diagrams
Sankey diagrams start off as one arrow that splits into two or more points. This shows how all of the energy in a system is
transferred into different stores.
3. 8.3 In a closed system what happens to the total energy of that system when there are energy
transfers?: where there are energy transfers in a closed system there is no net change to the total energy in that system
4. 8.4 Identify the different ways that the energy of a system can be changed: a) through work done by forces b)
in electrical equipment
c) in heating
5. Energy is transferred by one of the following four types of energy pathway:: .mechanical work - a force moving an
object through a distance
.electrical work - charges moving due to a potential difference
.heating - due to temperature difference caused electrically or by chemical reaction .radiation - energy transferred as a wave eg
light, infrared, sound - the Sun emits light radiation and infrared radiation
6. Describe how heating can change the energy of a system: Heating changes the energy stored within a system by
increasing the energy of the particles that make up that system
This either raises the system's temperature or, produces a change of state (eg. solid to liquid)
An example of the energy change by heating is electrical energy to thermal energy
7. Describe how work done by forces can change the energy of a system: -
When Work is Done against frictional forces, energy is transferred, increasing the temperature of the moving object and the
contact surface. When a force is used to move an object, energy is transferred (because the object has moved) and we say that
Work is Done
An example of the energy change by work done by forces is kinetic energy to thermal energy
8. Describe an example of how work done in electrical equipment can change the energy of a system: An
example of the energy change by work done when a current flow is chemical energy to electrical energy to thermal energy
(Chemical energy from the battery is converted to electrical energy in the components and then transferred to heat in wires)
9. 8.5 Describe how to measure the work done by a force: .Find the direction of the force vector and the direction of
motion
.Find the displacement of your object
.Find the force on the object
.Multiply Force × Distance
.Label your answer in joules
, .work done(J) = force(N) x distance moved in the direction of the force (m)
10. 8.5 Energy transferred (joule, J) is equal to...: work done (joule, J)
11. 8.7 Describe and calculate the changes in energy involved when a system is changed by work done by
forces (give an example): Bringing water to a boil in an electric kettle
Electricity through the element of the kettle increases its internal (thermal) energy which increases the internal (thermal) energy
of the water which increases the temperature of the water
(to calculate this select the right equation from the equation sheet)
12. 8.10 Explain, using examples, how in all system changes energy is dissipated so that it is stored in less
useful ways: No system is perfect. Whenever there is a change in a system, energy is transferred and some of that energy is
dissipated.
Dissipation is a term that is often used to describe ways in which energy is wasted. Any energy that is not transferred to useful
energy stores is said to be wasted because it is transferred to the surroundings.
For example - for a radio or set of speakers the electrical work is transferred into useful sound waves and thermal energy is
dissipated causing a rise in the internal energy store (temperature) of the surroundings
13. 8.11 Mechanical processes become wasteful when...: cause a rise in temperature so dissipating energy in heating
them surroundings
14. 8.12 Define power (and have an exmaple): The rate at which energy is transferred
(An example that illustrates the definition of power is by comparing two electric motors if:
They lift the same weight
They are lifted by the same height
One lifts it faster than the other
The motor that lifts the weight faster is said to have more power
This is because the work done does not depend on time, only the force (weight) and the distance lifted)
15. 8.14 Recall that one watt is equal to...: one joule per second ( J/s) 16. 9.10 Explain ways of reducing
unwanted energy transfer through lubrication: Reducing the friction between two surfaces can reduce this unwanted
energy transfer. Friction is sometimes reduced by placing rollers or ball bearings between the surfaces but, most often, oil is
used to lubricate the surfaces and allow them to slide smoothly over each other.
17. 10.1 Describe the structure of the atom, limited to the position, mass and charge of protons, neutrons and
electrons: The nucleus contains: Protons - positively charged particles with a relative atomic mass of one unit
Neutrons - no charge, and also with a relative atomic mass of one unit
Almost all of the atom is empty space, but moving around the nucleus there are: Electrons - negative charge with almost no mass
(1/2000 the mass of a proton or neutron)
18. 10.3 Describe the differences between series and parallel circuits: In series circuits, the different components are
connected in a line, end to end, between the positive and negative of the power supply. In parallel circuits, each component
is separately connected to the positive and negative of the supply.
-In a series circuit, the current is the same at all points
