Shape and Space 7
2 marks · EasyExplain, using reasoning, why the volume of a cylinder increases if the height is doubled but the radius stays the same.
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Common mistakes: Thinks the volume doubles only if both radius and height double.; Thinks volume does not change.
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Marking points
M1 · 1 mark · States or uses the formula for volume of a cylinder (), or explains connection between volume and height.
A1 · 1 mark · Correctly explains that if height is doubled, volume also doubles (and gives a reason).
Worked solution
The volume of a cylinder is , where is radius and is height.
If the radius stays the same but the height is doubled, volume becomes .
So the volume also doubles.