Pressure in liquids and gases
2 marks · NormalSome machines, such as bulldozers, use wide caterpillar tracks instead of wheels. Explain why this design helps the machines move on soft ground.
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Wide tracks spread the weight over a larger area, reducing the pressure on the ground, so the machine is less likely to sink.
Must show: Reference to increased area, Reduced pressure, Less likely to sink
Also accept: Lower pressure makes the ground less likely to give way
Common mistakes: Confusing force and pressure
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Marking points
B1 · 1 mark · Mentions large area reduces pressure
B2 · 1 mark · Explains lower pressure means less sinking into soft ground
Worked solution
The wide tracks increase the area in contact with the ground, so the same weight creates less pressure, making the machine less likely to sink.