Energy Transferred by Working
Energy and Thermal Physics

Shifting energy between stores - Teaching approaches

Classroom Activity for 11-14

A Teaching Approach is both a source of advice and an activity that respects both the physics narrative and the teaching and learning issues for a topic.

The following set of resources is not an exhaustive selection, rather it seeks to exemplify. In general there are already many activities available online; you'll want to select from these wisely, and to assemble and evolve your own repertoire that is matched to the needs of your class and the equipment/resources to hand. We hope that the collection here will enable you to think about your own selection process, considering both the physics narrative and the topic-specific teaching and learning issues.

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Fuels for warming and lifting

Energy Transferred by Working
Energy and Thermal Physics

Fuels for warming and lifting

Classroom Activity for 11-14

What the Activity is for

To introduce the idea that a chemical store can be emptied to do lifting (filling a gravitational store) or warming (filling a thermal energy store).

What to Prepare

  • A model steam engine linked to a drive shaft so as to be able to lift a load
  • A small burner set up to warm up water, preferably to near boiling in a short length of time

Safety note: Make sure you have practised with the steam engine, that it has been well maintained and that you are familiar with the latest CLEAPSS advice on the use of such engines.

What Happens During this Activity

Take a fixed volume of fuel and burn it to warm up some water. Then take a similar volume and use it to lift a load, pointing out the necessary losses due to some warming happening at the same time.

This activity introduces a key aspect of energy stores: they can be used to warm things up, or lift (and move) them. Emphasise these two possibilities. You might also draw attention to the need for both the fuel and the air – the chemical store that we are dealing with here is the fuel-plus-air, not one or the other.

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Focusing on energy changes

Energy Transferred by Working
Energy and Thermal Physics

Focusing on energy changes

Classroom Activity for 11-14

What the Activity is for

The purpose of this activity is to emphasise the point that care must be taken when selecting aspects of a process to describe in terms of energy.

What to Prepare

  • Two interactive objects, which offers a choice of changes to study (download below)

We provide an image, but you can use any single image that you want, so that you can explore the process of choosing what to study in your own context.

What Happens During this Activity

Launch the first interactive object, then discuss the placement of the box that decides what you'll study and describe. What are you going to include and exclude? Why are you including or excluding those pieces?

If you want to use your own photograph, first export the interactive object, then replace the image file (image.jpg) with your own image. Your own image must be named image.jpg.

Launch the second interactive object, then choose where to place the box, so defining the change carefully. Discuss where you will start and where you will end the change as you run through the photograph sequence. What are you going to include and exclude? Why are you including or excluding these processes?

If you want to use your own photographs, first export the interactive object, then replace the image files with your own. Your own must be named image1.jpg, image2.jpg, image3.jpg, image4.jpg and image5.jpg. You'll find it helpful if the images record exactly the same piece of space but at different times.

Resources

Download the interactive for this activity.

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Describing processes with energy stores

Energy Transferred by Working
Energy and Thermal Physics

Describing processes with energy stores

Classroom Activity for 11-14

What the Activity is for

Sharing energy among stores.

Here you can relate an everyday description of a simple situation (perhaps a car running down a hill) to how the energy is shared out amongst the stores. Later you can alter the energy shared amongst the stores to see how this affects the position of the car on the hill, so relating the energy description with where the car is and how fast it is going.

What to Prepare

  • a model car on a hill
  • a supply of orange fluid
  • beakers labelled as different stores (labels can be downloaded, see below)

What Happens During this Activity

First walk through the process that you have decided to study. Identify the start and finish points as snapshots. With the stores to hand, describe the process both physically and in terms of the filling and emptying of the named stores.

Later, with a more confident class, you might choose to fill the sotres to different levels and ask what the possibilities are for the physical description for that distribution of energy amongst the stores.

Resources

Download labels to use with activity.

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The BIG pendulum

Pendulum
Energy and Thermal Physics

The BIG pendulum

Classroom Activity for 11-14

What the Activity is for

Demonstrating energy changes.

This activity involves a discussion of the energy changes associated with a pendulum moving to and fro and probes the idea of energy dissipation.

What to Prepare

  • A simple pendulum hung from the lab ceiling with a big pendulum bob on the end of a strong, thin length of cord
  • This linked interactive object and the means to display it

The impact of this interactive demonstration depends on the quality of the pendulum. A big bob on the end of a long cord will sweep impressively back and forth, capturing the attention of the pupils. (A colleague, who likes to have maximum impact with his demonstrations, uses a ten-pin bowling ball as his pendulum bob!)

What Happens During this Activity

Set the pendulum up at the front of the room and gather the class around. Give the pendulum plenty of build-up (the best pendulum you'll see in your lifetime) and set it going to and fro. Describe the energy changes:

Energy is continuously shifted from the gravitational store of the bob (in the Earth's field) to the kinetic store of the bob, and back to the gravitational store … and so on.

Focus attention on the fact that as time goes by the bob does not reach the same height on its return path. It seems that the gravitational and kinetic stores are leaking.

Emphasise the point by asking a pupil to take a steady nerve test. This involves the pupil holding the bob to his or her chin and releasing it. As the bob sweeps back towards the chin, will the pupil have the nerve to hold still, convinced that it is impossible for the bob to return to a height greater than its starting point? Does the pupil really believe in physics?

Of course, the bob always falls short and this leads to discussion of energy dissipation. As the bob sweeps back and forth, warming occurs. The energy level in the gravitational and kinetic stores is gradually reduced as energy is shifted to the thermal store of the surrounding air.

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