Page 149 - Physics

Pressure

The pressure at a certain point in the liquid Therefore, the hole at the bottom of the can
is proportional to the height of the liquid will spurt water to the furthest distance.
column above that point. The larger the Note that, liquid pressure increases with
height above a point, the larger the pressure depth. This explains why the wall of a dam
at that point. Thus, the holes on the can that
are at the same level (depth) experience the is made much thicker at the bottom than at
same pressure and the liquid will be spurted the top, as shown in Figure 7.14.
to the same distance. This is because the
pressure in liquid acts in all directions. It Thin wall
is also equal at the same depth, as shown
in Figure 7.12. Thick
wall

Figure 7.14: Dam

Consider a liquid that has been
released into a communicating vessel

Figure 7.12: Water spurting from holes at shown in Figure 7.15. When water or
the same level any other type of liquid is poured into a
communicating vessel, it will attain the
The holes punched at different levels
on the can will spurt water to different same level in all of its tubes regardless of
distances. The hole at the top has the least shape of the tubes.
height of liquid above it. This means that
the water spurts the shortest distance.
This distance increases with an increase
in the height above the hole, as shown in
Figure 7.13. A B C D

Figure 7.15: Pressure in a communicating
vessel

The fact that the liquid rises to the same
vertical height in all tubes is an indication
that pressure at all points of similar depth
in a liquid is the same. A liquid always
fi nds its level in a vessel in which it is

Figure 7.13: Water spurting from holes at contained. Pressure at A, B, C and D in
different heights Figure 7.15 is the same.

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Physics Form 1 Final.indd 143 16/10/2024 20:57