Page 148 - Physics
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Physics for Secondary Schools
Therefore, Acti vity 7.3
Normal force(Weight)
Pressure(P)! Aim: To demonstrate the
Area(A)
variation of pressure with
Weight mg
P = = depth of a liquid.
area A
Materials: Water, large can or big
Ahρg plastic bottles, nail,
P=
A hammer, ruler and
= hρg cellotape
Procedure
1. Take a large can and punch two holes
Pressure in liquids = height of the on opposite sides using a nail and
liquid column × density of liquid × hammer but at the same height from
acceleration due to gravity. the bottom of the can.
2. Seal the holes using a cellotape.
Thus, pressure at any point in a liquid at 3. Pour water into the can to a certain
rest depends on a depth of the liquid and height. Simultaneously, unseal both
the density of the liquid. It is important holes and record the horizontal
distance covered by the water stream
to note that pressure in liquid does not from each hole.
depend on the area of the container. 4. Stop pouring water.
5. Punch holes at different heights on
Characteristics of pressure in liquids a second bottle can but on the same
Pressure in liquids is characterised by the side.
following parameters. 6. Seal the holes as in step 2.
1. Pressure in a liquid increases with 7. Pour water into the can to a height
depth. above both holes.
2. Pressure in a liquid acts equally in 8. Simultaneously, unseal the holes
all directions. while keeping the water height
3. Pressure in a liquid increases with an constant by continuously pouring
increase in the density of the liquid. water into the can.
Mercury exerts more pressure than 9. Observe and record the horizontal
an equal volume of water because distance covered by water streams
mercury is denser than water. from each hole.
Variation of liquid pressure with Questions
depth (a) What causes the water to spurt out
of the holes?
The pressure in a liquid increases with (b) From this activity, what can you
depth of the liquid. conclude about pressure in liquids?
142
Student’s Book Form One
Physics Form 1 Final.indd 142 16/10/2024 20:57
