NOTE: These FREE Frames are samples of a much larger, and growing, collection. They are not presented here in an unbroken sequence. The complete set, with both FREE and NOT FREE Frames provides explanation without gaps.
thermal energy transfers I: gaining and losing energy
E1: 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
• Loss of energy by a body can cause cooling
• Energy can become thinly spread in the large surroundings
• Objects or systems can store, gain and lose energy; energy can transfer between them
thermal energy transfers II: temperature difference
E2: 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)
thermal energy transfers III: representing energy transfers
E3: Thermal energy transfers III
Syllabus / specification points:
• Energy transfers naturally from warmer (higher temperature) to cooler (lower temperature)
• A kettle supplies energy to water
• Some energy from a kettle with hot water transfers directly to the surroundings
• The water stores some energy, and you can make a hot drink.
• Some energy from the hot drink transfers directly to the surroundings. The surroundings get a little warmer, but the energy spreads thinly.
• You get a little energy from the hot drink, but energy also spreads from you to the surroundings.
thermal energy transfers IV: the effects thermal energy gain
E3b: Thermal energy transfers IV
Syllabus / specification points:
• Money and energy transfer
• Money can be stored in a bank, and in a ‘piggy bank’
• Energy can be stored by hot material
• Transfer of energy to material can cause it to ‘change state’ – to melt or to boil
• Transfer of energy to material can cause its temperature to increase
Processes of thermal energy transfers
E4: Processes of thermal energy transfer
Syllabus / specification points:
• CONVECTION is a process of energy transfer involving movement of hotter liquids and gases through cooler material.
• The liquids and gases carry their energy store with them; energy can then transfer to the cooler materials that they mix with.
• The movement can become ‘convection currents’
• CONDUCTION is a process of energy transfer from particle to particle.
• Conduction happens best in metals, because there are strong forces between the particles
• RADIATION is a process of energy transfer by waves, similar to light waves but invisible to us
conservation of energy
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 without resistive forces
E10.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
E10.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 replace the dissipated energy
Energy, provisional list, July 2021
E1 Thermal energy transfers I
E2 Thermal energy transfers II
E3 Thermal energy transfers III
E3.B. Effects of gain
E4 Processes of thermal energy transfer
ENERGY SPECIAL: some essential Physics of energy balance and temperature stability of oranges, cakes and planets
E4.B ‘Higher rate’ isn’t the same as ‘more’
E4.C Balance and imbalance of thermal energy transfer
E4.D Energy balance of a planet
E4.E. Changing the atmosphere
E4.F Changing the atmosphere, changing the energy balance
E4.G Higher and higher temperature?
E5 Work: mechanical energy transfer
E6 Work and kinetic energy
E7 How to calculate kinetic energy
E8 Work and extra gravitational potential energy
E9 Calculating extra gravitational potential energy
E10 Conservation of energy
E10.B Conservation of energy: motion with/without resistive force
E10.C Conservation of energy: falling without resistive force
E10.D Conservation of energy: falling with/without resistive force
E10.E Conservation of energy: motion without resistive force
E10.F Conservation of energy: motion with resistive force
E10.G Conservation of energy: changes of KE + GPE during orbit
E11 Energy stores
E11.B Energy storage by stretched springs and wires
E11.C More energy transfers: in chemical changes
E11.D More energy transfers: by waves
E11.E More energy transfers: in electric circuits
E11.F More energy transfers: in nuclear changes
E12 Heating water I
E13 Heating water II
E14 The snowman is melting
E15 Boiling dry
E16 Power I
E17 Power II
E18 Thermal conductors and thermal insulators
E19 Reducing energy loss through a wall
E20 Efficiency I
E21 Efficiency II
E22 Efficiency III
E23 Reducing dissipation due to friction
E24 Coal is old
E25 Biofuels
E26 Water flow
E27 Water waves
E28 Underground I
E29 Underground II
E30 Wind turbines
E31 Solar panels
E32 Solar cells
E33 The nuclear power industry I
E34 The nuclear power industry II
E35 Clean energy?
Copyright (c) David Brodie, 2019-2021
Photography: Adobe Stock