Physics
Project
Subject:
Pressure
By:
Cem Salur
Grade:
10/A
To:
Mr. Sinan Kosak
Physics
Project
Subject:
Pressure
By:
Cem Salur
Grade:
10/A
To:
Mr. Sinan Kosak
Content
Test 3
Test 4
What is pressure?
The word pressure has an exact meaning.
It is defined as the force acting normally
(perpendicularly) per unit area. Pressure
measured as Pascal “Pa”.
Pressure
=
Force
Area
N
m
2
Pa
Question
A boy of mass 40 kg balances
evenly on two stilts, each an area
of 8 m
2
in contact with the ground.
What is the pressure exerted on
one stilt?
Content Page
Answer
Pressure= Force / area
Force= 400 N
Pressure=?
Area= 8 m
2
So
Pressure= 400 N / 8 m
2
Pressure= 50 Pa
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Density
Density is the mass per unit
volume of the substance, and it is
sometimes given the symbol “ρ”.
ρ = m / v ρ is density (kg/m3)
m is mass (kg)
v is volume (m3)
Pressure in liquids
The pressure in liquid
increases with depth. The
width or shape of the
container doesn’t effect
the pressure. The pressure
is effected by the density
of the liquid. As the figure
show on the right side. In
liquids pressure acts all
directions not only
vertically.
The main formula is:
Pressure=force (weight) /
Area
hAdg / A
Which becomes => hdg
so
Pressure= hdg
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What is Atmospheric
Pressure?
On the earth we are living under a
large volume of air. Air has weight
and as a result the atmosphere
exerts a pressure not only on the
Earth’s surface but on objects on
the earth. Atmospheric pressure
is normally expressed in Newton's
per meter square or pascals (Pa).
The average value is 100 000 Pa
approximately. It gets less as one
goes up through the Earth’s
atmosphere until it becomes
virtually zero at a height of about 8
km.
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Mercury Barometer
This is a long glass tube,
sealed at one end, with
the other end dipped in
a dish of liquid mercury.
Atmospheric pressure
sometimes measured in
millimeters of mercury
rather than pascal.
Mercury is used in a
barometer rather than
any other liquid,
because it is so dense.
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Aneroid Barometer
This is the barometer which
people hang in the hall to
forecast the weather. It isn’t
so accurate as mercury
barometer. But it is simpler
to read and to carry. In the
middle of barometer is
sealed metal box with
flexible sides. Most of the air
has been removed from the
box, so it is squashed by
the atmosphere. The greater
the pressure, the more the
sides are pushed in, and the
further the pointer moves
round.
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Manometer
Manometers are
used to measure
gas and liquid
pressure. The
height difference
tells you the extra
pressure.
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Test I
Content Page
Test II
Test III
Test IV
