Pressure under a solid
2 marks · EasyExplain why a person lying flat on thin ice is less likely to fall through than a person standing, even if their mass is the same.
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Lying flat increases area under the body, which reduces the pressure on the ice, making it less likely to break.
Also accept: When lying down, the person’s weight spreads over a larger area, so the pressure is less and there is less chance of the ice breaking.
Common mistakes: Explaining in terms of weight only and not area.; Not mentioning pressure.
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Marking points
B1 · 1 mark · Mentions area increases when lying down.
B2 · 1 mark · Mentions pressure on the ice decreases or ice less likely to break.
Worked solution
When lying flat, the person’s weight is spread over a larger area. This reduces the pressure on the ice, making it less likely to break.