Page 119 - PortalToEnglish_3_SB_SE

4 CLIL: Science

Pressure

A What do you think will happen to a balloon if it is taken
underwater?
B Look at the highlighted words in the text and find their
definitions in a dictionary.
C Listen, read and check your answer to activity A.
t w
t w
a
s
The easie
The easie
s
a
o
Have you ever felt your ears pop when diving The easiest way to
o
y t
y t
unders
y
illing
unders
tand this is b
y
understand this is by illing
tand this is b
really deep underwater? What you felt was a understand this is by illing
result of water pressure. There is more pressure a balloon with air . D o this at
o this at
. D
a balloon with air. Do this at
a balloon with air
a balloon with air. Do this at
sea le
underwater than there is on land. When you sea le v el, wher e the pr e s s sur e e
sea level, where the pressure
e
el, wher
e the pr
v
sur
sea level, where the pressure
v
w
is 1 atm. Then dive underwater
is 1 atm. Then di
is 1 atm. Then di
at
dive down, the irst place you feel the change in is 1 atm. Then dive underwater
at
e under
e under
er
v
er
w
© MM Publications
w
pressure is in your ears. This is because your ears with the balloon. Under w at er , , , ,
w
w
with the balloon. Underwater,
with the balloon. Under
at
with the balloon. Under
with the balloon. Under
with the balloon. Underwater,
er
er
er
at
at
the pressure will compress the
the pr
always have air inside them. The higher pressure the pressure will compress the
ompr
s the
s the
sur
e
s
s
sur
the pr
e
s
s
e will c
e
e
e will c
ompr
y it
air in the balloon in the same way it
a
air in the balloon in the same way it
air in the balloon in the same w
compresses the air, and this is what makes our air in the balloon in the same w a y it
e
. As the
s the air in our ears
ears feel so strange. c c ompr e s s se s the air in our ears . As the
compresses the air in our ears. As the
se
ompr
compresses the air in our ears. As the
ease
e incr
e incr
ease
ome
, the balloon will bec
s
s
pressure increases, the balloon will become
pr pr
, the balloon will bec
e
sur
sur
ome
e
s
s
When we stand on land at sea level, we are pressure increases, the balloon will become
smaller
smaller. At a depth of 10 m, the balloon will be
smaller
t a depth of 10 m, the balloon will be
. A
. A
t a depth of 10 m, the balloon will be
standing in 1 atmosphere (atm) of pressure. smaller. At a depth of 10 m, the balloon will be
e. A
as on the sur
t a depth of
t a depth of
as on the sur
half the siz
e. A
ac
ac
half the siz
half the size it was on the surface. At a depth of
half the size it was on the surface. At a depth of
e it w
e it w
This is the normal pressure of the air in the half the siz e it w as on the sur f f f ac e. A t a depth of
20 m, wher
20 m, wher
20 m, where the atmosphere is 2 atm higher than
20 m, wher
20 m, wher
spher
spher
spher
e the atmo
spher
20 m, where the atmosphere is 2 atm higher than
e the atmo
e is 2 atm higher than
e the atmo
e the atmo
e is 2 atm higher than
e is 2 atm higher than
e is 2 atm higher than
atmosphere that we live in every day. 20 m, wher e the atmo spher e is 2 atm higher than
d of it
ac
d of it
d of it
ac
d of it
ac
at the sur
at the sur
e, the balloon will be a thir
ac
at the sur
at the sur
at the sur f f f f f ac e, the balloon will be a thir d of it s s s s s
e, the balloon will be a thir
e, the balloon will be a thir
e, the balloon will be a thir
at the surface, the balloon will be a third of its
at the surface, the balloon will be a third of its
When we go underwater, the pressure increases original size.
because the water above us also creates
pressure. The deeper you go, the higher the
pressure; for every 10 metres (m) of depth, the Science in action
Scuba divers have to understand how air changes under
pressure increases by another 1 atm.
pressure because it lets them know how long they can stay
underwater. At great depths, the pressure is very high and it
compresses the air in their tank. In a way, this means that they
have ‘less’ air to breathe. So the deeper they go, the less time
they can stay there before they have no more air left.
D Read again and complete the
diagram below.
sea level pressure = atm balloon is full size
depth = m pressure = 2 atm balloon is
its original size
balloon is a third
depth = 20 m pressure = atm of its original size
Over to you...
Discuss.
If you fill a balloon with air on
the surface and take it down
to 20 m, it will become much
smaller. If you take it back up to
the surface again, what do you
think will happen? Why?
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