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Pressure Pascalrsquos Principle
PRESSURE OF A FLUID
Barometer
air pressure pressure = height of mercury column
Gauge pressure ndash pressure above the atmospheric pressure
absolute (total) pressure =gauge pressure + atmospheric press
Pressure is produced by the weight of the fluid above the surface
forcepressure = ------ area
weight of fluid= ---------------- area
mg= ----- area
density volume g= ------------------------- area
density (area height) g= -------------------------------- area
pressure = density height g
P = ρhg gauge pressure
SI units
pressure Nm2 = Pascals (Pa)
density kgm3
height (depth) m
P = ρhg + P0 absolute pressure
Standard atmospheric pressure
760 mm Hg asymp 30 in Hg
Calculate 1 atm in Pascals
P = ρgh
ρHg = 136 x 103 kgm3
g = 98 Nkg h = 0760 mP = 1013 x 105 Pa
Why does a barometer use mercuryand not water
If p = 1 atmosphere = 1013 x 105 Paρ = 100 gcm3 = 100 x 103 kgm3
Find height
103 m
Pressure of fluid depends on depth
ldquoWater seeks its own levelrdquo
Pressure does not depend on volumeonly on height (depth)
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
PRESSURE OF A FLUID
Barometer
air pressure pressure = height of mercury column
Gauge pressure ndash pressure above the atmospheric pressure
absolute (total) pressure =gauge pressure + atmospheric press
Pressure is produced by the weight of the fluid above the surface
forcepressure = ------ area
weight of fluid= ---------------- area
mg= ----- area
density volume g= ------------------------- area
density (area height) g= -------------------------------- area
pressure = density height g
P = ρhg gauge pressure
SI units
pressure Nm2 = Pascals (Pa)
density kgm3
height (depth) m
P = ρhg + P0 absolute pressure
Standard atmospheric pressure
760 mm Hg asymp 30 in Hg
Calculate 1 atm in Pascals
P = ρgh
ρHg = 136 x 103 kgm3
g = 98 Nkg h = 0760 mP = 1013 x 105 Pa
Why does a barometer use mercuryand not water
If p = 1 atmosphere = 1013 x 105 Paρ = 100 gcm3 = 100 x 103 kgm3
Find height
103 m
Pressure of fluid depends on depth
ldquoWater seeks its own levelrdquo
Pressure does not depend on volumeonly on height (depth)
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
Gauge pressure ndash pressure above the atmospheric pressure
absolute (total) pressure =gauge pressure + atmospheric press
Pressure is produced by the weight of the fluid above the surface
forcepressure = ------ area
weight of fluid= ---------------- area
mg= ----- area
density volume g= ------------------------- area
density (area height) g= -------------------------------- area
pressure = density height g
P = ρhg gauge pressure
SI units
pressure Nm2 = Pascals (Pa)
density kgm3
height (depth) m
P = ρhg + P0 absolute pressure
Standard atmospheric pressure
760 mm Hg asymp 30 in Hg
Calculate 1 atm in Pascals
P = ρgh
ρHg = 136 x 103 kgm3
g = 98 Nkg h = 0760 mP = 1013 x 105 Pa
Why does a barometer use mercuryand not water
If p = 1 atmosphere = 1013 x 105 Paρ = 100 gcm3 = 100 x 103 kgm3
Find height
103 m
Pressure of fluid depends on depth
ldquoWater seeks its own levelrdquo
Pressure does not depend on volumeonly on height (depth)
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
Pressure is produced by the weight of the fluid above the surface
forcepressure = ------ area
weight of fluid= ---------------- area
mg= ----- area
density volume g= ------------------------- area
density (area height) g= -------------------------------- area
pressure = density height g
P = ρhg gauge pressure
SI units
pressure Nm2 = Pascals (Pa)
density kgm3
height (depth) m
P = ρhg + P0 absolute pressure
Standard atmospheric pressure
760 mm Hg asymp 30 in Hg
Calculate 1 atm in Pascals
P = ρgh
ρHg = 136 x 103 kgm3
g = 98 Nkg h = 0760 mP = 1013 x 105 Pa
Why does a barometer use mercuryand not water
If p = 1 atmosphere = 1013 x 105 Paρ = 100 gcm3 = 100 x 103 kgm3
Find height
103 m
Pressure of fluid depends on depth
ldquoWater seeks its own levelrdquo
Pressure does not depend on volumeonly on height (depth)
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
forcepressure = ------ area
weight of fluid= ---------------- area
mg= ----- area
density volume g= ------------------------- area
density (area height) g= -------------------------------- area
pressure = density height g
P = ρhg gauge pressure
SI units
pressure Nm2 = Pascals (Pa)
density kgm3
height (depth) m
P = ρhg + P0 absolute pressure
Standard atmospheric pressure
760 mm Hg asymp 30 in Hg
Calculate 1 atm in Pascals
P = ρgh
ρHg = 136 x 103 kgm3
g = 98 Nkg h = 0760 mP = 1013 x 105 Pa
Why does a barometer use mercuryand not water
If p = 1 atmosphere = 1013 x 105 Paρ = 100 gcm3 = 100 x 103 kgm3
Find height
103 m
Pressure of fluid depends on depth
ldquoWater seeks its own levelrdquo
Pressure does not depend on volumeonly on height (depth)
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
pressure = density height g
P = ρhg gauge pressure
SI units
pressure Nm2 = Pascals (Pa)
density kgm3
height (depth) m
P = ρhg + P0 absolute pressure
Standard atmospheric pressure
760 mm Hg asymp 30 in Hg
Calculate 1 atm in Pascals
P = ρgh
ρHg = 136 x 103 kgm3
g = 98 Nkg h = 0760 mP = 1013 x 105 Pa
Why does a barometer use mercuryand not water
If p = 1 atmosphere = 1013 x 105 Paρ = 100 gcm3 = 100 x 103 kgm3
Find height
103 m
Pressure of fluid depends on depth
ldquoWater seeks its own levelrdquo
Pressure does not depend on volumeonly on height (depth)
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
Standard atmospheric pressure
760 mm Hg asymp 30 in Hg
Calculate 1 atm in Pascals
P = ρgh
ρHg = 136 x 103 kgm3
g = 98 Nkg h = 0760 mP = 1013 x 105 Pa
Why does a barometer use mercuryand not water
If p = 1 atmosphere = 1013 x 105 Paρ = 100 gcm3 = 100 x 103 kgm3
Find height
103 m
Pressure of fluid depends on depth
ldquoWater seeks its own levelrdquo
Pressure does not depend on volumeonly on height (depth)
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
Why does a barometer use mercuryand not water
If p = 1 atmosphere = 1013 x 105 Paρ = 100 gcm3 = 100 x 103 kgm3
Find height
103 m
Pressure of fluid depends on depth
ldquoWater seeks its own levelrdquo
Pressure does not depend on volumeonly on height (depth)
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
Pressure of fluid depends on depth
ldquoWater seeks its own levelrdquo
Pressure does not depend on volumeonly on height (depth)
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
ldquoWater seeks its own levelrdquo
Pressure does not depend on volumeonly on height (depth)
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
More pressure at greater depth
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
Measure blood pressure at upper arm
same height as heart
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
Pascalrsquos Principle ndash The pressure in an enclosed fluid is constant throughout the fluid
p1 = p2
F1 F2
--- = ---A1 A2
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
A = 1 cm2A = 50 cm2
1 N
p1 = p2
1 N F2
------- = ------ 1 cm2 50 cm2
50 N
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
If piston on left moves 10 cmwhat distance does piston on rightmove
work1 = work2
F1 d1 = F2 d2
(1) (10) = (50) d2
02 cm
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
Hydraulic lift
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
Area of brake cylinder gt area of brake line
force of brake cylinder gt force of brake pedal
hydrostatic pressure
hydrostatic pressure
