2. words meaning
Pressure
The force acting per unit area of
the surface.
Pascal SI unit of pressure.
Thrust
Total force acting vertically on
the surface of a body.
Fluid The substance which can flow.
Manometer
A simple device used to measure
liquid pressure.
Atmospheric pressure
The pressure exerted by the
layer of air around the earth
barometer
The apparatus used for
measuring the air pressure

3.  Effect of force on a given area is called pressure.
 Pressure depends on two factors. They are: force
applied and area over which force acts.
 The formula of pressure is: Pressure=Force/Area.
 Pressure can also be defined in terms of another
force called thrust.
 The force acting on a body perpendicular to its
surface is called thrust.
 So, we can also define pressure as thrust per unit
area is Pressure=Thrust/Area.
 The SI unit of pressure is Pascal (Pa).

4.  It is easier to cut an apple from the sharper side
than blunt because the sharper side has less
area.
 Porters wear turbans while carrying heavy loads
on heads. By doing this pressure on their heads
gets reduced due to the increase in area of
contact.
 Wooden sleepers are kept below the railway
lines so that there is less pressure of the train on
the ground and railway lines do not sink into
the ground.

5.  Unlike solids, the liquids do not have a definite
shape. They take the shape of the containing vessels.
 The pressure in liquids is not thrust per unit area.
instead it depends it depends upon the depth and
density of the liquid.
 Fluids have weight so they exert pressure on the base
and walls of the container.
 The pressure at a depth in a liquid depends upon
two factors:
1) The height of the liquid column.
2) The density of the liquid.

6.  A manometer is a simple device used to
measure liquid pressure.
 It has a U – shaped tube which is fixed to a
wooden board having a scale.
 The U – tube is filled with coloured water
such that its limbs are half filled.
 One end of the U – tube is open, the other
end is fixed to a rubber tube which in turn
is connected to a thistle funnel .
 This improvised apparatus is called as
manometer .

7.  The pressure exerted by water in the oceans
increases with depth.
 When deep sea fishes are brought up to the
surface of the sea, their body flow at a Very high
pressure.

8.  Like all gases, air also have weight hence
exerts pressure.
 The force exerted by the atmosphere on
unit area is called atmospheric pressure.
 Air exerts huge pressure in every
direction.

9.  A barometer is an instrument used to
measure atmospheric pressure.
 It consists of long and thin tube filled
with mercury and closed at one end.
 The open end of the tube is placed in a
small trough full of mercury.
 The pressure exerted by air on the
mercury of trough is able to hold
certain height of the mercury column.
 When the air pressure is low, the
mercury will move down.
 When the air pressure increases, the
height of the mercury column increases

10.  The edge of the knife is made sharper increase
pressure.
 The sole of sport shoes have spikes have spikes
to increase the grip through pressure.
 In vacuum cleaner a low pressure is created
inside with the help of a fan and this low
pressure helps in the working of vacuum
cleaner.
 The straw helps us to drink juice because the
atmospheric pressure is exerted on the surface of
the juice.

11.  The pointed end of a high heeled shoe exerts
more pressure than what an elephant’s flat
exerts.
 It is due to the upward force exerted by water
that we are able to swim.
 The pressure of water vapours in a streaming
pressure cooker, cooks the food faster.
 The first mercury barometer was made by an
Italian scientist terriceilliinm 1643.
 submarines are built of hard thick sheets of
metal to withstand the high pressure of water.

12.  The effect of force on a given area is called
pressure.
 The SI unit of pressure is Pascal(Pa)equal to 1
Newton per meter square the pressure exerted
by air is called atmospheric pressure.
 Atmospheric pressure is measured with
barometer.
 A liquid exerts pressure in all direction.
 At the same depth the pressure is same in all
direction.
 Liquid pressure increases with depth.
 Liquid pressure is measured with manometer.