Pressure in liquids
Task 1
a) Complete the sentences using the words in the box. Then add arrows to the beaker to
show how the water particles move.
Everything, including liquids, are made up of tiny.........................
The particles move around and as they do this they ....................
with the ....................................... they come into contact with.
The force of the particles hitting a surface causes .......................
Pressure comes from all ........................... .
directions
particles
collide
surfaces
pressure
The picture shows a flask full of water with a pump on the top.
The flask has holes in the bottom.
b) Imagine the plunger was pushed down, draw the water coming
out of the holes at the bottom and then complete the sentence
below by crossing out the incorrect words.
The water comes out of all / some of the holes.
The water squirts out the same / differently from each hole.
Pressure in solids / liquids is the same / different in all
directions.
3) This flask is filled with water and has three
spouts on one side, 1, 2 and 3.
a) Which spout is deepest? .........................
b) Which spout do you think the water will come
out of the fastest? ....................................
c) Draw on the diagram what you think the water
coming out of each spout will look like.
d) What is the rule here? Cross out the incorrect
word.
Pressure in liquids decreases / increases with
depth.
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Pressure in liquids
Task 2
Look at the picture below and answer the questions.
a) Which diver is deepest? ......................................................................................................
b) How many metres lower is Lucy? ........................................................................................
c) How much more pressure is there on Lucy than on Brenda? Show your working out.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
d) Using the data from the diagram of the divers plot a graph to show how water pressure
changes with depth.
Use your graph to complete the following statements:
i)
The water pressure at a depth of 7.5 m is ...........................................................
ii)
The depth at which the water pressure is 32 000 Pa is .........................................
Going further
Deep sea diving can be very dangerous. As the diver goes deeper the weight of the water above
creates a larger pressure on the diver. As the pressure outside the diver’s body increases the
pressure of the compressed air they breathe in also increases and more air is absorbed into the
body. This can cause decompression sickness when they ascend.
e) If a diver goes very deep underwater they can suffer from decompression sickness (also
known as ‘the bends’). Find out what ‘decompression sickness’ is.
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Pressure in liquids
Teaching notes and answers
Ask students to use the sheet to predict what they think will happen in the diagrams then show
them a demonstration or a video clip.
Task 2
Suggested websites for decompression sickness research (links available at time of publishing).
http://adventure.howstuffworks.com/outdoor-activities/water-sports/question101.htm
http://www.netdoctor.co.uk/travel/diseases/decompression_sickness.htm
Task 1
1) Everything, including liquids, are made up of tiny particles. The particles move around and
as they do this they collide with the surfaces they come into contact with. The force of the
particles hitting a surface causes pressure.
Pressure comes from all directions.
2) The water comes out of all of the holes.
The water squirts out the same from each hole.
Pressure in liquids is the same in all directions.
3) a) Spout 3
b) Spout 3
c)
d) Pressure in liquids increases with depth.
Task 2
a)
b)
c)
d)
Lucy
6m
80 000 Pa – 20 000 Pa = 60 000 Pa
i) 75 000 Pa ii) 3.2 m
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