Pressure in Liquids and Gases
4 marks · NormalFigure 1 shows a metal can with several small holes at the same height, positioned around its base. The can is filled with water and the streams of water coming from each hole are observed.
Describe what will be observed from the holes when the can is filled with water.
Explain how this experiment shows that pressure in a liquid acts equally in all directions at a certain depth.
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.
Show answer
(a) Water jets out of each hole to an equal distance from the can. · must show Water leaves all holes at same height, Streams reach equal distances
(b) Since water jets out equally from holes in all directions at the same depth, the pressure at those points must be the same, showing pressure acts equally in all directions at that depth. · must show Reference to same depth, Equal streams/pressure in all directions, Conclusion about equal pressure
Common mistakes: Describes only one direction.; Misses idea of equal pressure at same depth.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States water streams shoot equally/far from all holes.
M1 (b) · 1 mark · Links same height/depth to same pressure.
A1 (b) · 1 mark · States pressure causes jet of water to be equal in all directions.
B2 (b) · 1 mark · Concludes that this demonstrates pressure acts equally in all directions at a point.
Worked solution
a) The water coming out of each hole forms a stream that travels the same distance from the can, in all directions.
b) This happens because the pressure at each hole (all at the same depth) is the same. The equal pressure forces the water outwards equally, showing that pressure at a given depth in a stationary liquid is equal in all directions.