a very simple presentation about pressure

1. Tools of pressure
Manometer
Barometer
The application of straw
Pressure gauge

2. What is pressure ?
Pressure is the ratio between the force
exerted upon specific area
P = ‫ــــــــــــــــ‬
Pressure has the unit of N/M2 this unit is
called Pascal in the SI system of units
pressure may also use unit of Ib/in2
F
A

3. The manometer
Manometer is a tool for measuring the
pressure
Figure.1 Figure.2

4. Manometer depends on 3 factors;
1. the Height of the column of the fluid
[H]
2. The density of the fluid [ρ]
3. The gravitaional constant [g] which
equal 9.81 m/s2
So the pressure in manometer = H x ρ x
g

5. The barometer
Measurement tool for pressure of gases
[atmospheric pressure]
It depends on the direct proportional
between the pressure of the air
[atmospheric pressure] and the
height of the column of the mercury.

6. The straw
The straw depends on the idea of the
barometer that;
[as the atmospheric pressure decreases
the height of the column of liquid
increases]

7. 1. When you take a smell by opening your
lungs;
2. You increase the volume where the
same air is separated,
3. Then the density of air is increasing.
4. The pressure of the air is decreasing
and the air transport from high pressure
to law.
5. The pressure in the straw get smaller. It
makes the height of the liquid’s column
increases

9. Pressure gauge
Measurement tool for pressure

10. The measured fluid flow through the
pump to make the needle to move.
Where the needle stops, the read value
is the value of the pressure

11. Gauge pressure Vs total
pressure
Total pressure =
the pressure on the surface of the liquid
+ the atmospheric pressure [gauge
pressure]
Gauge pressure =
total pressure – the pressure on the
surface of the liquid

12. Problems