Fluid Flow

Laminar flow is smooth and predictable. Turbulent flow is chaotic.

Uniform Motion

A=Cross-Sectional Area

Uniform Motion

A=Cross-Sectional Area

Changing the radius of the pipe--Conservation of mass

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.

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 _________ asgreat as the speed of the cars

still on the bridge.

A. one fourthB. one half C. twiceD. four times

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

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

A. one fourthB. one half C. twiceD. four times

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.

I

II

ww

w

h

hh

A. one fourthB. one half C. equally

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 _________ asgreat as that of of duct I .

D. twiceE. four times

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

Conservation of Energyfor a horizontal pipe

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?

1 2 3

A. P2 > P1 > P3

B. P3 > P1 > P2

C. P2 > P1 = P3

D. P1 = P2 = P3

E. P1 > P2 > P3

hidden

Conservation of Energyfor a vertical pipe

1

2

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.

A. greater than

B. equal to

C. less than

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

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.