Work done
Here, the language can be a barrier to understanding rather than the ideas. The everyday use of the term work is ill defined whereas in physics it has a strict definition (force x distance) and is used a tool to make quantitative descriptions of particular situations. You may wish to use the term ‘mechanical work’ to help clarify this as a very specific quantity that is measured in Joules particularly as students may encounter other types of work (e.g. electrical work).
At the same time it would be wise to provide a generic definition of power as the rate at which work is done as this may help avoid confusion later on.
The effect of work done on an object to change its shape is dealt with in the related list GCSE 9 Change of shape
Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.
Defining work done
This page can provide the source material for a simple set of notes although the content on work done when the force is at an angle to the direction of motion can over complicate things and so be cautious. It includes an explanation of the use of force-displacement graphs to calculate the work done on an object.
Episode 214: Work Done by a Force
Use this first practical resource from the IOP to establish the definition of work done and then to reinforce understanding of efficiency in energy transfer. The questions at the end can be used to confirm learning of the material covered.
Calculating Work Done
Give this resource to your students so that they can test their understanding of the topic. There are other related links on the page that they can also use, particularly the one for Power which provides a good definition, explanation and set of questions.
Cutting Edge Materials: Practicals
This resource contains a number of activities – the work on a coil one is the most applicable one here.
Use this experiment with your students to collect real data and then to calculate work done. It makes use of memory metal with extension work on applications of memory metal. You could carry out the experiment with an ordinary expendable spring as an alternative.
Episode 218: Mechanical Power
Although originally designed for A level this activity provides some clear, well structed example calculations for work done (and power). It does provide a modified to the power equation (‘power = force x velocity’) which you may not wish to use. The personal power calculation is a student favourite, though you have to be mindful of students’ feelings about sharing what their weight is with others. The questions at the end tie things up neatly.
Measure the power of a person and results
In this video clip the power of a person running up stairs is investigated. The subsequent calculations are explained.
