- Demonstrate that objects can move at uniform speed with no forces acting,
eg friction-free pucks on glass, a trolley on an air track, videos of ice skating, curling. Draw on pupils' experiences and support with use of ICT simulations.
- Show that introducing forces produces changes in speed - accelerations - not steady speeds.
- Introduce the idea that the larger the mass that the force acts on, the smaller will be the change in speed. Continue with the athletics and sports context and ask questions,
eg
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How far can you skate on smooth ice?
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How does a sprinter get a good start?
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Why are shot-putters massive and runners slim, but both need to be muscular?
- Laboratory investigations,
eg ask pupils to
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arrange friction-free movement and show that constant speed needs no force, using the equipment above
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measure the force needed to get objects of different mass moving
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try to keep applying constant force and use sensing equipment to observe the change in speed, eg up slopes, on different surfaces
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use secondary data to compare the performance of cars, eg starting acceleration with engine size or with mass of car
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- give examples of movement without force,
eg skating
- give examples of situations,
eg athletics, cars, classroom objects, in which forces increase or decrease speed
- make simple generalisations,
eg the larger the force, the greater the increase of speed
- make comparisons using information from secondary sources
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