Question 1

Flow rate: Water flows through a pipe having a varying width. More water flows per second through the wide section than through the narrow section because there is more room for it to flow.

Accepted Answer

A) True 
 B)False

Question 2

Pressure in a fluid: Fluid fills the container shown in the figure. At which of the indicated points is the pressure greatest?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  The pressure is the same at each of the labeled points.

Question 3

Bernoulli's principle: Air is flowing through a rocket nozzle. Inside the rocket the air has a density of 5.25 kg/m3 and a speed of 1.20 m/s. The interior diameter of the rocket is 15.0 cm. At the nozzle exit, the diameter is 2.50 cm and the density is 1.29 kg/m3. What is the speed of the air when it leaves the nozzle?

Accepted Answer

A)  123 m/s 
B)  176 m/s 
C)  88.0 m/s 
D)  45.7 m/s 
E)  29.3 m/s

Question 4

Buoyancy: Salt water is more dense than fresh water. A ship floats in both fresh water and salt water. Compared to the fresh water, the volume of salt water displaced by the ship is

Accepted Answer

A)  greater than the volume of fresh water. 
B)  less than the volume of fresh water. 
C)  the same as the volume of fresh water.

Question 5

Pressure in a fluid: The two water reservoirs shown in the figure are open to the atmosphere, and the water has density 1000 kg/m3. The manometer contains incompressible mercury with a density of 13,600 kg/m3. What is the difference in elevation h if the manometer reading m is 25.0 cm?

Accepted Answer

A)  1.58 m 
B)  4.20 m 
C)  3.75 m 
D)  3.40 m 
E)  3.15 m

Question 6

Pressure in a fluid: At a certain depth in the ocean, the absolute pressure is p. If you go to twice that depth (treating the water as incompressible)

Accepted Answer

A)  the absolute pressure will be 2p. 
B)  the absolute pressure will be less than 2p. 
C)  the absolute pressure will be greater than 2p. 
D)  the gauge pressure will not change. 
E)  the gauge pressure will increase but will not double.

Question 7

Pressure in a fluid: A cubical box, 5.00 cm on each side, is immersed in a fluid. The gauge pressure at the top surface of the box is 594 Pa and the gauge pressure on the bottom surface is 1133 Pa. What is the density of the fluid?

Accepted Answer

A)  1000 kg/m3 
B)  1100 kg/m3 
C)  1220 kg/m3 
D)  2340 kg/m3 
E)  12,000 kg/m3

Question 8

Bernoulli's principle: In a section of horizontal pipe with a diameter of 3.00 cm the pressure is 5.21 kPa and water is flowing with a speed of 1.50 m/s. The pipe narrows to 2.50 cm. What is the pressure in the narrower region if water behaves like an ideal fluid of density 1000 kg/m3?

Accepted Answer

A)  4.00 kPa 
B)  7.50 kPa 
C)  5.82 kPa 
D)  6.42 kPa 
E)  4.61 kPa

Question 9

Buoyancy: A wooden raft has a mass of 50 kg. When empty it floats in water (density  with 69% of its volume submerged. What mass of sand can be put on the raft without it sinking?

Accepted Answer

The answer of Buoyancy: A wooden raft has a mass...

Question 10

Bernoulli's principle: As the speed of a moving fluid increases, the pressure in the fluid

Accepted Answer

A)  increases. 
B)  remains constant. 
C)  decreases. 
D)  may increase or decrease, depending on the density of the fluid.

Question 11

Buoyancy: A person who weighs 550 N empties her lungs as much as possible and is then completely immersed in water (of density 1000 kg/m3) while suspended from a harness. Her apparent weight is now 21.2 N. What is her density?

Accepted Answer

A)  1050 kg/m3 
B)  1040 kg/m3 
C)  1030 kg/m3 
D)  960 kg/m3 
E)  56.1 kg/m3

Question 12

Bernoulli's principle: Consider a very small hole in the bottom of a tank  in diameter filled with water to a height of  Find the speed at which the water exits the tank through the hole.

Accepted Answer

A)  3.13 m/s 
B)  9.80 m/s 
C)  31.8 m/s 
D)  34.9 m/s

Question 13

Buoyancy: A piece of wood is floating in a bathtub. A second piece of wood sits on top of the first piece, and does not touch the water. If the top piece is taken off and placed in the water, what happens to the water level in the tub?

Accepted Answer

A)  It goes up. 
B)  It goes down. 
C)  It does not change. 
D)  This cannot be determined without knowing the volume of the top piece of wood.

Question 14

Flow rate: Water, of density 1000 kg/m3, is flowing in a drainage channel of rectangular cross-section. The width of the channel is 15 m, the depth of the water is 8.0 m and the speed of the flow is 2.5 m/s. At what rate is water flowing in this channel?

Accepted Answer

A)  2.0 × 105 kg/s 
B)  2.0 × 103 kg/s 
C)  3.0 × 105 kg/s 
D)  3.0 × 103 kg/s 
E)  3.0 × 102 kg/s

Exam 12: Fluid Mechanics

Flow rate: Water flows through a pipe having a varying width. More water flows per second through the wide section than through the narrow section because there is more room for it to flow.

Pressure in a fluid: Fluid fills the container shown in the figure. At which of the indicated points is the pressure greatest?

Buoyancy: Salt water is more dense than fresh water. A ship floats in both fresh water and salt water. Compared to the fresh water, the volume of salt water displaced by the ship is

Pressure in a fluid: The two water reservoirs shown in the figure are open to the atmosphere, and the water has density 1000 kg/m³. The manometer contains incompressible mercury with a density of 13,600 kg/m³. What is the difference in elevation h if the manometer reading m is 25.0 cm?

Pressure in a fluid: At a certain depth in the ocean, the absolute pressure is p. If you go to twice that depth (treating the water as incompressible)

Pressure in a fluid: A cubical box, 5.00 cm on each side, is immersed in a fluid. The gauge pressure at the top surface of the box is 594 Pa and the gauge pressure on the bottom surface is 1133 Pa. What is the density of the fluid?

Bernoulli's principle: In a section of horizontal pipe with a diameter of 3.00 cm the pressure is 5.21 kPa and water is flowing with a speed of 1.50 m/s. The pipe narrows to 2.50 cm. What is the pressure in the narrower region if water behaves like an ideal fluid of density 1000 kg/m³?

Buoyancy: A wooden raft has a mass of 50 kg. When empty it floats in water (density with 69% of its volume submerged. What mass of sand can be put on the raft without it sinking?

Bernoulli's principle: As the speed of a moving fluid increases, the pressure in the fluid

Buoyancy: A person who weighs 550 N empties her lungs as much as possible and is then completely immersed in water (of density 1000 kg/m³) while suspended from a harness. Her apparent weight is now 21.2 N. What is her density?

Bernoulli's principle: Consider a very small hole in the bottom of a tank in diameter filled with water to a height of Find the speed at which the water exits the tank through the hole.

Buoyancy: A piece of wood is floating in a bathtub. A second piece of wood sits on top of the first piece, and does not touch the water. If the top piece is taken off and placed in the water, what happens to the water level in the tub?

Flow rate: Water, of density 1000 kg/m³, is flowing in a drainage channel of rectangular cross-section. The width of the channel is 15 m, the depth of the water is 8.0 m and the speed of the flow is 2.5 m/s. At what rate is water flowing in this channel?