NOTE: These Talk-About Frames are samples of a much larger, and growing, collection. Scroll down to see the current list.
thermal energy transfers I
Frame EN1
EN1: Thermal energy transfers I
Syllabus / specification points:
• The Sun acts as a huge store of energy, emitting energy to space
• The Earth has a lower temperature than the Sun, and gains energy from it
• Energy transfers from a mug of hot energy to the cooler surroundings, by thermal processes – conduction, convection and radiation
• Loss of energy by a body can cause cooling
• Energy can become thinly spread in the large surroundings; we say it is dissipated
• Objects or systems can store, gain and lose energy; energy can transfer between them
thermal energy transfers II
Frame EN2
EN2: Thermal energy transfers II
Syllabus / specification points:
• Energy natural transfers from objects or systems at higher temperature to ones at lower temperature
• Our bodies are usually at higher temperature than our surroundings, so we lose energy and we must replace it by ‘burning’ food
• We can reduce the rate of energy loss by heating the spaces we live in, thus reducing temperature difference
• We can reduce the rate of energy loss by using layers of insulation (clothing)
Frame EN6
EN6: Work and kinetic energy
Syllabus / specification points:
• Work must be done to change motion (accelerate) and to overcome resistance to motion
• Energy is needed for doing work
• There must be a source of energy, such as fuel+oxygen; fuel may be a fossil fuel
• Moving objects have an energy store due to motion, called kinetic energy
• Energy transferred to overcome resistance becomes dissipated
how to calculate kinetic energy
Frame EN7
EN7: how to calculate kinetic energy
Syllabus / specification points:
• An object with kinetic energy has the ability to do work on other objects with which it collides, and so it is a store of energy
• The quantity of stored energy depends on the mass of the body and its speed
• Kinetic energy = 1/2 mv2
work and extra gravitational potential energy
Frame EN8
Frame EN8
EN8: Work, extra height and extra gravitational potential energy
Syllabus / specification points:
• A falling object can do work, and so acts as a store of energy
• The extra energy it has due to the potential to fall is its gravitational potential energy, GPE
• At the end of a fall, the energy may become dissipated
conservation of energy
Frame EN10
EN10: Conservation of energy
Syllabus / specification points:
• Energy cannot be destroyed
• The total energy at the end of every process is the same as at the beginning
• However, energy can become thinly spread by thermal processes, and become dissipated
conservation of energy: motion with + without resistive forces
Frame EN10.B
EN10.B: Conservation of energy during motion, with and without resistive forces
Syllabus / specification points:
• The total energy at the end of every process is the same as at the beginning, so if there are no resistive forces the work done by a cyclist produces a matching increase in kinetic energy
• Where there are resistive forces work must be done to overcome them, resulting in dissipation of energy
• When resistive force is the same size as the driving force all of the work done by the cyclist results in dissipation and there is no gain in kinetic energy
conservation of energy: motion without resistive forces
Frame EN10.C
EN10.C: Conservation of energy: falling without resistive forces
Syllabus / specification points:
• The Moon has less mass than the Earth, so has smaller gravitational field strength, g
• The total energy at the end of every process is the same as at the beginning, so if there are no resistive forces the gravitational potential energy at the start of a fall matches the kinetic energy at the end
conservation of energy: motion with + without resistive forces
Frame EN10.D
EN10.D: Conservation of energy: falling with and without air resistance
Syllabus / specification points:
• The total energy at the end of every process is the same as at the beginning, so if there are no resistive forces the gravitational potential energy at the start of a fall matches the kinetic energy at the end
• However if there is air resistance then there is some heating and air movement caused by the fall; then some energy is dissipated and kinetic energy at the end of the fall is less than the gravitational potential energy at the start
conservation of energy: motion without resistive forces
Frame EN10.E
EN10.E: Conservation of energy: motion without resistive force
Syllabus / specification points:
• The total energy at the end of every process is the same as at the beginning, so if there are no resistive forces the gravitational potential energy at the highest point matches the kinetic energy at the lowest point
• A pendulum, such as a playground swing, loses and gains gravitational potential energy and kinetic energy, in turn
• When there are is no need for work to be done to overcome resistive forces then there is no dissipation
conservation of energy: motion with resistive forces
Frame EN10.F
EN10.F: Conservation of energy: motion with resistive force
Syllabus / specification points:
• The total energy at the end of every process is the same as at the beginning, so if there are resistive forces the gravitational potential energy at the highest point matches the total of dissipated energy plus kinetic energy at the lowest point
• There is loss of energy, by dissipation, during every swing, so the maximum gravitational potential energy and the maximum kinetic energy gradually become smaller
• A source of energy is needed to compensate for the dissipated energy
conservation of energy: motion with resistive forces
Frame EN10.G
EN10.G: Conservation of energy: changes of GPE and KE during orbit in space
Syllabus / specification points:
• The physics that applies to playground swings also applies to large objects in space
• Pluto is sometimes closer to the Sun and sometimes further away
• It has kinetic energy (due to its motion) and gravitational potential energy (due to the Sun’s gravitational field)
• When it is closest to the Sun it’s gravitational potential energy is minimum, so kinetic energy is maximum
• When it is furthest from the Sun it’s gravitational potential energy is maximum, so kinetic energy is minimum
work and kinetic energy
Energy, provisional list, May 2021
Comp: completed and ready, but so far unpublished
E1 Thermal energy transfers I FREE
E2 Thermal energy transfers II FREE
E3 Thermal energy transfers III Comp
E4 Processes of thermal energy transfer Comp
E4.B Rates of emission of radiation Planned
E5 Work: mechanical energy transfer Comp
E6 Work and kinetic energy FREE
E7 How to calculate kinetic energy FREE
E8 Work and extra gravitational potential energy FREE
E9 Calculating extra gravitational potential energy Comp
E10 Conservation of energy FREE
E10.B Conservation of energy: motion with/without resistive force FREE
E10.C Conservation of energy: falling without resistive force FREE
E10.D Conservation of energy: falling with/without resistive force FREE
E10.E Conservation of energy: motion without resistive force FREE
E10.F Conservation of energy: motion with resistive force FREE
E10.G Conservation of energy: changes of KE + GPE during orbit FREE
E11 Energy stores Comp
E11.B Energy storage by stretched springs and wires Planned
E11.C More energy transfers: in chemical changes Planned
E11.D More energy transfers: by waves Planned
E11.E More energy transfers: in electric circuits Planned
E11.F More energy transfers: in nuclear changes Planned
E12 Heating water I Comp
E13 Heating water II Comp
E14 The snowman is melting Planned
E15 Boiling dry Planned
E16 Power I Comp
E17 Power II Comp
E18 Thermal conductors and thermal insulators Comp
E17 Reducing energy loss through a wall Comp
E20 Efficiency I Comp
E21 Efficiency II Comp
E22 Efficiency III Comp
E23 Reducing dissipation due to friction Comp
E24 Coal is old Planned
E25 Biofuels Planned
E26 Water flow Planned
E27 Water waves Planned
E28 Underground I Planned
E29 Underground II Planned
E30 Wind turbines Planned
E31 Solar panels Planned
E32 Solar cells Planned
E33 The nuclear power industry I Planned
E34 The nuclear power industry II Planned
E35 Clean energy? Planned
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Copyright (c) David Brodie, 2019-2021
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