Pressure in Liquids and Gases
2 marks · NormalSome people think that atmospheric pressure only acts downwards. Give two reasons, based on everyday or laboratory evidence, that show atmospheric pressure acts equally in all directions.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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Also accept: Water jets sideways from holes in a can.; Magdeburg hemispheres are held together from all sides.
Common mistakes: Only gives upward/downward examples; Misses sideways evidence
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Marking points
B1 · 1 mark · Everyday or lab example: e.g., can with holes jets sideways, or suction cups stick to a wall sideways.
B2 · 1 mark · Second valid example, e.g., Magdeburg hemispheres stick because pressure acts from all sides.
Worked solution
One example: when a can with holes at the same level is filled with water, streams shoot out sideways, showing pressure acts sideways, not just downwards. A second example: suction cups stick to vertical surfaces because atmospheric pressure pushes them onto the wall from the side.