- Elicit pupils' ideas about the effect of exerting pressure on a container of liquid. Offer them balloons or syringes filled with water to determine whether they can reduce the volume.
- Show a diagram of a simple hydraulic system where the liquid is transferred from a reservoir of unit area to one of 10 times unit area, and ask pupils to predict the force with which it will lift the plunger when a force of 10N is applied. Take votes on the outcome. Most will intuitively predict that the force is diminished rather than magnified. Reference to the distance moved by the applied force may help the understanding of this counter-intuitive outcome.
- Demonstrate,
eg using video, the ability of a hydraulic jack to lift large loads,
eg a car, with little effort, or model this with water-filled tubes.
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- apply the particle model of matter to explain why liquids are incompressible and gases are compressible
- apply the concept of transmission of pressure to predict the resulting force
- describe some effects and uses of liquids under pressure,
eg fire hoses, hydraulic systems
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