Fluids amp Elasticity Pressure in liquids Measuring and using pressure amp Buoyancy Pressure in Liquids What is the pressure at a depth d Pressure in Liquids Absolute Pressure ID: 622711
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Slide1
Knight: Chapter 15
Fluids & Elasticity
(
Pressure in liquids, Measuring and using pressure, & Buoyancy)Slide2
Pressure in Liquids
What is the pressure at a depth
d
?Slide3
Pressure in Liquids
Absolute Pressure,
Gauge Pressure,
What is the pressure at a depth
d
?Slide4
Pressure in Liquids
Force per unit area
that a liquid exerts on
a submerged objectDepth dependent
and NOT volume dependent
i.e.
Swim twice as deep, then twice as much weight of water above you produces twice as much pressure on you.Acts equally in all directions i.e.: Your ears feel the same pressure under water regardless of your head’s orientation.Independent of shape of container:
Regardless of the shape of a container, pressure is the same at any particular depth.Slide5
Quiz Question 1
Water pressure provided by a water tower is
greater
if the toweris taller.
holds more water.
Both 1. and 2.
None of the above.Slide6
Pressure in Liquids
A connected liquid in
hydrostatic equilibrium
rises to the same height in all open regions of the container.
The pressure is the
same
at all points on a
horizontal line through a connected liquid in hydrostatic equilibrium.Slide7
Suppose we change
p
0
to
p
1
…
What happens to the pressure in the fluid?
Pressure in LiquidsSlide8
Pascal’s
Principle
A change in pressure
at one point in an incompressible fluid appears undiminished at all points in the fluid. Slide9
Solving Hydrostatic ProblemsSlide10
ManometersSlide11
ManometersSlide12
BarometersSlide13
BarometersSlide14
BarometersSlide15
The Hydraulic lift
How does
F
2
relate to
F
1
?Slide16
The Hydraulic lift
How does
F
2
relate to
F
1
?Slide17
The Hydraulic lift
Suppose we lift the car higher…
How does
d2 relate to d1? Slide18
Suppose we lift the car higher…How does d
2
relate to
d1?
Notice:
The distance is
divided
by the same factor as that by which the force is multiplied.statement of energy conservation. The Hydraulic liftSlide19
The hydraulic lift at a car repair shop is filled with oil. The car rests on a 25-cm-diameter piston. To lift the car, compressed air is used to push down on a 6.0-cm-diameter piston.What does the gauge read when a 1300 kg car is 2.0 m above the compressed-air piston?
i.e. 15.7:
Lifting a carSlide20
Buoyancy
Q: Why do things feel lighter underwater (or even float)?
Imagine
a block in a fluid…
h
1
h
2
F
1
F
2
h
p
1
p
2Slide21
The buoyant force is equal to the
weight of the
fluid displaced
.
Buoyancy