Fluid Flow

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Fluid Flow
Laminar flow is smooth and predictable. Turbulent
flow is chaotic.
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Uniform Motion
ACross-Sectional Area
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Uniform Motion
ACross-Sectional Area
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Changing the radius of the pipe--Conservation of
mass
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The Continuity Principle
The volume flow rate of a fluid in a pipe is
constant.
The effect is that the speed of the fluid will
depend on the radius of the pipe. The fluid flows
faster in a narrower part of the pipe and flows
slower in a wider part of the pipe.
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Two lanes on each of the upper and lower levels
of a bridge must all merge into a single lane
because of construction. If the traffic is
bumper-to-bumper throughout, the speed of the
cars that have already merged must be _________
as great as the speed of the cars still on the
bridge.
A. one fourth B. one half C. twice D. four times
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Poll
Suppose that a blood flows through an artery that
has plaque built up on a certain section of the
artery and decreases the radius of the artery in
that section. This section of the artery is
referred to as a blockage. As the blood flows
from the normal part of the artery into the
section with the blockage, the speed of the blood

1. Increases
2. Decreases
3. Remains constant

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Poll
Pipe A has a radius R, and Pipe B has a radius
2R. If water flows from Pipe A and into Pipe B,
the speed of the fluid in pipe B is

1. 2vA
2. Sqrt(2)vA
3. 4vA
4. 1/2 vA
5. 1/4 vA
6. Equal to vA

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Air passes from one ventilation duct (I) to
another (II) that is twice as high and twice as
wide. Duct II has a cross-sectional area
_________ as great as that of of duct I .
I
w
w
h
A. one fourth B. one half C. twice D. four
times
II
w
h
h
To the extent that the air in the ducts can be
treated as incompressible, the air in duct II
will have _________ as much speed as the air in
duct I.
A. one fourth B. one half C. equally
D. twice E. four times
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If blood flows from one blood vessel into another
with two thirds the diameter of the first, you
will have to multiply the speed of blood in the
first blood vessel by ________ to find its speed
in the second blood vessel.
A. 0.44 B. 0.67 C. 1.50
D. 2.25
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Conservation of Energyfor a horizontal pipe
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Water flows through a long horizontal pipe of
variable diameter. Three very tall, narrow
standpipes, 1, 2, and 3, connect to different
sections of the horizontal pipe. These standpipes
are all open at the top, and water rises partway
to the top of each. The tops of the three columns
of water are not shown, so you cannot see how
high the water rises in each standpipe. Which of
the following correctly compares the height h to
which the water rises in each?
A. P2 gt P1 gt P3 B. P3 gt P1 gt P2 C. P2 gt P1
P3
hidden
1
2
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D. P1 P2 P3 E. P1 gt P2 gt P3
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Conservation of Energyfor a vertical pipe
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You can readily observe that when you run water
from a faucet at a moderate steady flow rate, the
stream of water narrows as it descends. This
implies that the speed of the water at point 2 is
_______ the speed at point 1.
?
1
2
?
A. greater than B. equal to C. less than
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Poll
Air flows faster on the top of an airplane wing
than on the bottom of a airplane wing. On which
side is the pressure greater?

1. Bottom of the wing
2. Top of the wing
3. Neither, the pressure is the same on the top and
   bottom

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Poll
A tennis ball is hit with top-spin. Is the
pressure greater on the top of the ball or on the
bottom of the ball?

1. Top of the ball
2. Bottom of the ball
3. Neither, the pressure is the same on the top and
   bottom.