Page 204 - New Medley 5 Semester 2

e in ated football is heavier because it has air inside it. is shows that air
has weight.
Air Occupies Space

• Hands-on Learning
Activity

Take an empty glass. Turn it upside down and place it on the surface of water in
a tub. Gently press it down. Does water enter the glass?

Water does not enter the glass as it is full of air. is shows that air occupies space.

us, air has weight and occupies space.
Knowledge Zone
Air Exerts Pressure Pressure exerted by air is called

Anything that has weight exerts pressure. Gases atmospheric pressure. The

exert pressure in all directions on the inner instrument used to measure air
walls of the container that holds them. pressure is called barometer.

Activity • Analysing

Take a capped plastic bottle filled with water. Take a pin and poke a hole into the side of the

bottle close to the bottom. Remove the pin.
Observe what happens.
Remove the bottle cap. Observe what happens now.

ere are two forces acting at the hole of the bottle.

Water pressure inside the bottle is trying to push

the water out of the pinhole. At the same time, the
air pressure outside the bottle is trying to keep the

water inside the bottle. When the bottle is capped,
the forces inside and outside the bottle remain equal

and water does not leak out of the pinhole.
Air pressure helps to fill a
But when the cap is removed, the air pressure above pitchkari and a syringe
the water becomes greater and forces the water to come out of the pinhole.

Uses of Air Pressure

 Air pressure is used to ll a pitchkari and a doctor’s syringe.

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