March 25, 2011
DRILL
1. Sketch the relationship between Pressure and
Volume
2. Sketch the relationship between 1/Pressure and
Volume
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DRILL
Pressure (psi)
60
40
30
20
10
0
0
5
10
15
20
25
30
35
Volume (mL)
Volume vs. 1/P
0.070
0.060
0.050
1/P
Pressure (psi)
50
0.040
0.030
0.020
0.010
0.000
0
5
10
15
20
Volume (mL)
25
30
35
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Boyle’s Law
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Robert Boyle (1627-1691) – from Ireland; chemist,
physicist, and inventor
Boyle’s Law – the pressure and volume of an ideal
gas are inversely proportional
Increase Pressure
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Increase Volume
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Decrease Volume
Decrease Pressure
PV = k
P1V1 = P2V2
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Principles of Fluid Technology
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Back to your chart.
What do you notice about the values for P x V?
Under constant temperature, the product of
pressure and volume for a fluid is a constant.
Boyle’s Law: P V = k
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Definitions
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Technology – the application of knowledge, tools, and skills to
solve problems and extend human capabilities.
Technology System – a group of subsystems working together to
solve problems and extend human capabilities.
Core Technologies – several engineering resources that are the
“building blocks” of all technology systems.
Volume – how much space an object occupies
Force – a push or pull
Pressure – a force applied over an area
Closed System – a system in which no fluid can enter or leave.
Open System – a system in which a fluid can enter or leave.
Fluid – a substance (as a liquid or a gas) that conforms to the
outline of its container
Fluid Technology – the technology of using fluid, either gas
(pneumatics) or liquid (hydraulic), to apply force or to transport.
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Worksheet #3
P=F/A
(Pressure = Force / Area)
PV = k
(Pressure x Volume = Constant)
P1V1 = P2V2
(Initial P x Initial V = Final P x Final V)
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Worksheet #4
A gas system has initial pressure and volume of 80 psi and 6 L. If
the volume changes to 10 L, what will the resultant pressure be in
psi?
Step 1: Write given information
P1 = 80 psi
V1 = 6 L
P2 = ?
V2 = 10 L
Step 2: Write the formula and solve
P1V1 = P2V2
(80 psi) x (6 L) = P2 x (10 L)
480 psi*L = P2 x (10 L)
10 L
10 L
P2 = 48 psi
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Worksheet #5
A sample of hydrogen gas is compressed from 300 cm3 to 2.5 cm3.
Its pressure is now 5 psi. What was the original pressure of the
helium?
Step 1: Write given information
P1 = ?
V1 = 300 cm3
P2 = 5 psi
V2 = 2.5 cm3
Step 2: Write the formula and solve
P1V1 = P2V2
P1 x (300 cm3) = 5 psi x (2.5 cm3)
P1 x (300 cm3) = 12.5 psi*cm3
300 cm3
300 cm3
P1 = 0.0417 psi
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Problem 7
1.
The diagram below illustrates how hydraulic brakes in a
car work. The pedal must be pressed with a force of 8 lbs.
The surface area of the piston connected to the pedal is 1
square inch. If the surface area of the piston connected to
the other end of the brake line is 1.5 square inch, what is
the force applied to that piston?
P1 = F1 / A1
P1 = P2
P2 = F2 / A2
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Problems
Solution:
Step 1: Write given information
P1 = ?
P2 = ?
F1 = 8 lbs.
F2 = ?
A1 = 1 in2
A2 = 1.5 in2
Step 2: Write the formula and solve for the unknowns
P1 = F1 / A1
P1 = (8 lbs) / (1 in2)
P1 = 8 psi
P1 = P2 = 8 psi
P2 = F2 / A2
F2 = P2 x A2
F2 = 8 psi x 1.5 in2 = 12 lbs.
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Problems
What is the mechanical advantage of this system?
MA = L / F
MA = (12 lbs)/ (8 lbs)
P1 = 8 psi
P2 = 8 psi
F1 = 8 lbs
F2 = 12 lbs
A1 = 1 in2
A2 = 1.5 in2
MA = 1.5
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Complete the fluid technology
problem sheet.
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