Air

Question 1

Pressure exerted by Air -

Answer 1

Atmospheric pressure is the pressure exerted by the
weight of air in the atmosphere of Earth (or that of
another planet).

Question 2

MORE -

Answer 2

All gases in the atmosphere exert pressure on
each other, the earth and the objects on earth
including humans.

The pressure exerted on a human body by
atmosphere is compensated by the pressure
exerted by the gases inside human body.

Question 3

Examples of pressure being exerted by Air-

Answer 3

Distortion of tin can or bottle

Closed Tin can half filled with boiling water.

The can will have hot water as well as steam.

Now, pouring cold water will make the steam
condense and become water.

This reduces air inside the can.

Since the pressure of air inside can becomes
lower than air outside, the can’s shape will
become distorted.

Question 4

Example -

Answer 4

Sucking a straw decreases pressure inside it, this
makes the outside atmospheric pressure become
higher and the fluid thus goes up through the
straw.

Question 5

Example -

Answer 5

Tyre tube bursts when over filled with air due to
the fact that the pressure inside the tube becomes
higher than the outer atmospheric pressure.

Question 6

Name the factor responsible for the increase of

speed of wind or cyclones.

Answer 6

Factors like wind speed, wind direction,
temperature and humidity contribute to the
development of cyclones

Question 7

Paheli kept an empty bottle made of plastic
inside a refrigerator. After few hours, when she
opened the refrigerator, she found the bottle had
collapsed. Explain the possible reason.

Answer 7

On cooling the air, contraction of air takes place.
The air inside the bottle contracts due to low
temperature. Hence, the bottle collapses due to the
outside pressure.

Question 8

The advanced technologies issue the alerts and

warnings of unexpected storm. Comment.

Answer 8

The technologies that include satellites and
radars issue the information of expected storm in
advance in the form of cyclone warnings. It is
issued in two stages, i.e. a cyclone alert or
cyclone watch is issued 48 h in advance of any
expected storm and cyclone warning is issued 24
h in advance. The message is broadcasted every
hour or half hour when a cyclone is nearest the
coast.