Energy Stores and Energy Transfer Pathways

The idea of energy and the suggestions of how to teach energy in school Physics lessons has changed recently. Rather than thinking of energy as a “thing”, teachers are now being encouraged by the exam boards and the Institute of Physics (http://www.iop.org) to talk about energy stores and energy transfer pathways.

One of the suggestions I heard recently being discussed on the Teaching Physics Podcast ( https://the.physicsteachingpodcast.com/ ) is the idea of taking snapshots of a system in time. For example: If we run an electrical motor connected to a battery for 5 minutes and we compare the energy stores before and after these 5 minutes we see that the chemical store in the battery has reduced while the kinetic & thermal stores in the motor and surrounding air has increased. What’s more, the increase in kinetic & thermal stores will exactly match the decrease in the battery’s chemical store. We should be able to show this mathematically using calculations.

Another shift in thinking comes with the word “heat”. Previously, heat was used to describe the energy associated with hot objects. The IOP now promote the word “heat” as being used only as a verb. So we can heat things and objects can be heated, but heat should not be a noun. There should be no such thing as heat. Instead, heating is an energy transfer pathway – a mechanism by which energy is transferred from one store to another.

I have produced a student revision video aimed at GCSE level Physics on Energy Stores and Energy Transfer Pathways. The video shows clearly how energy can be transferred from one store to another. The video then shows how to answer some typical GCSE exam questions.

Energy Stores & Pathways Revision Video by Plutonium Science

One final word of warning is the confusion that often arises about the difference between temperature, thermal energy and heating.

  • Temperature can be thought of as a measure of the kinetic energy of all particles in a substance – the higher the temperature, the faster the particles are vibrating/moving.
  • Thermal energy is a store. A mathematical quantity, measured in joules. A boiling kettle will have less thermal energy than an indoor swimming pool because there is much less water in the kettle, despite the temperature being a lot higher.
  • Heating, as I’ve said, is a transfer pathway. Energy can be transferred from one store to another through heating – whether that be heating by conduction or convection (using particles), or heating by radiation of an electromagnetic nature.

You know what they say: If you can’t stand the heat…

…You’re using the word incorrectly.

The Doc.

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