Forces at a Distance (moments, balance, pressure, hydraulics and pendulums)
Students are likely to have met balance, turning moments and pressure in their Key Stage 3 courses and so in many cases this topic will represent a more detailed and mathematical treatment of these ideas. The basic principles of turning moments are reasonably intuitive (as seen in young children’s understating of balancing see saws). However the numerical calculations can be challenging with an inverse relationship (increasing force, decreasing distance and vice versa). When studying pendulums the absence of an effect of mass on the time period continues to be counter intuitive, even for many A level students, and so the experimental exploration of this should be seen as just as valid as that of the effect of length. After all the experimental proof of a variable having no effect is just as important the ones that do.
This collection has some practical ideas and activities in each area and ends with some numerical questions.
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
Links and Resources
This is a resource to use towards the end of this topic when students feel comfortable about the key ideas. It’s very good because it challenges their thinking and is likely to lead to deeper understanding. Instead of the traditional beam, this activity uses a disc for thinking about moments. It’s simple and cheap to prepare given the clear instructions and pictures and the teacher notes give very good guidance on how to use it with a class to promote higher level thinking. There’s a lesson plan to accompany the teacher notes.
This set of cards, along with the teacher notes and lesson plan, are recommended because they do more than revise moments, they help students clarify and deepen their understanding of the topic. The objective is not just for students to classify the cards into always true, sometimes true or never true, but to have meaningful discussions or even arguments with other students about where a card should be placed. It’s this sort of discussion that really makes learning stick.
This golden oldie could do with a bit of a face lift but its useful for resources about the applications of the pendulum or moments to the playground. You want unit 705 which is pages 9-15 in the pdf document and before the lesson you might like to set some of the early questions about swings as a practical piece of homework to be carried out in the local playground, perhaps with a younger sibling for cover! There are teacher notes and answers on the first couple of pages but the questions themselves, although they could do with being re-typed in a more modern looking format, will certainly get students thinking.
This suite of resources use a real life context to consider pressure and hydraulic systems. The RNLI’s high speed lifeboats are useless if you can’t get them into the sea. The launcher shown in this film is an astonishing beast and the presentation and students worksheet that accompany the film will help students to apply what they know. There are some nice practical activities along with follow up calculations and graphical work but be aware that the superscripts aren’t correct in one place.
Although this resource is tagged as being suitable for key stage 3 students, the three documents about pressure are included here because they deal very well with hydraulic systems. It takes a bit of time to work out how the documents work together but the effort is repaid by the quality of advice and the ideas on offer. If you’re an experienced teacher, you could focus just on the hydraulics section and use the document on teaching and learning issues to really help your students get a deep understanding of the topic. If you are less familiar with this subject you will find all the documents worthwhile as they give a more rounded picture of the topic and help to relate it to other parts of the curriculum.
Using equations and carrying out calculations are an integral part of physics. Here are some useful worked examples and questions about moments which will save you having to write your own. They are on pages 25-27 of the book (pages 33-35 of the pdf document). Depending on the ability of the class, you might like to talk through the worked examples on the board before setting the questions. The answers are on page 126 (pdf page 134). The first page gives some useful teaching points. The other two pages could be printed out as they stand for students.