2. Pressure Measurement
FORWARD
Hydrostatic
Pressure
BACK
Pressure
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FIRST Type of
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Pressure Measurement
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Measuring
Buoyancy
Instruments
Applications Evaluation
3. PRESSURE
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• Pressure units are a measure of force
BACK acting over unit area.
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• It is most commonly expressed in
pounds per square inch (psi) or
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SLIDE sometimes pounds per square foot (psf)
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in English units; or Pascals (Pa) in
metric units, which is the force in
Newtons per square meter (N/m²).
Pressure = Force, F Exercise
Area, A 2.1
5. HYDROSTATIC PRESSURE
FORWARD
• A vertical column of fluid exerts a pressure due
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to the column’s weight.
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• The relationship between column height and
fluid pressure at the bottom of the column is
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regardless of vessel width or shape.
Exercise
2.2, 2.3
= Mass density of fluid in kilograms per cubic meter (metric)
or slugs per cubic foot (British)
=Weight density of fluid in Newton per cubic meter (metric)
or pounds per cubic foot (British)
9. BUOYANCY
FORWARD
•Buoyancy is the upward force exerted on an object
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immersed or floating in a liquid.
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•The weight is less than it is in air, due to the weight of the
displaced fluid. The upward force on the object causes the
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weight loss, called the buoyant force, and is given by:
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where
B = The buoyant force in pounds
y = The specific weight in pounds per cubic foot
V = the volume of the displaced liquid in cubic feet.
11. PASCAL LAW
FORWARD
The pressure applied to an enclosed liquid (or
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gas) is transmitted to all parts of the fluid and to
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the walls of the container.
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Exercise
2.8
13. MEASURING INSTRUMENTS
FORWARD
BACK Diaphragms, The devices that change
Capsules, their shape when pressure
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and Bellows is applied.
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21. EXERCISE 2.1
FORWARD
BACK The liquid in a container has a total weight of 152
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kN, and the container has a 8.9 m² base. What is
the pressure on the base?
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BACK >>
22. EXERCISE 2.2 & 2.3
FORWARD
BACK What is the depth in a lake, if the pressure is 0.1
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MPa?
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SLIDE What is the pressure at the base of a water tower
LAST that has 35m of head?
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23. EXERCISE 2.5 & EXTRA
FORWARD
BACK What pressure in psi corresponds to 98.5 kPa?
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FIRST
The atmospheric pressure is 14.5 psi. If the
SLIDE absolute pressure is 2,865.6 psfa, what is
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the gauge pressure?
What is the gauge pressure in (a) kPa, and (b)
N/cm², at a distance 5.5 ft below the
surface of a column of water?
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24. EXERCISE 2.6 & 2.7
FORWARD
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What is the buoyant force on a plastic cube with
2.5m sides, floating in water, if three-quarters of
HOME the block is submerged?
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What is the apparent weight of a 3.7m³ block of
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SLIDE wood totally immersed in acetone? Assume the
specific weight of wood is 8.5 kN/m³.
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25. EXERCISE 2.8
FORWARD
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In figure below, if the area of the small piston A S is
8.2 in²,and the area of the large piston A L is 2.3 ft²,
HOME what is the force FL on the large piston, if the force
FIRST FS on the small piston is 25N?
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26. EXERCISE 2.9 & 2.10
FORWARD
BACK
The liquid in a manometer has a specific weight of
8.5 kN/m³. If the liquid rises 83 cm higher in the lower
HOME pressure leg, what is difference in the pressure
FIRST between the higher and the lower legs?
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What is the liquid density in a manometer, if the
difference in the liquid levels in the manometer
tubes is 1.35m, and the differential pressure
between the tubes is 7.85 kPa?
BACK >>