Question 1

Salt water has greater density than fresh water. A boat floats in both fresh water and in salt water. Where is the buoyant force greater on the boat?

Accepted Answer

A)  salt water 
B)  fresh water 
C)  Buoyant force is the same in both. 
D)  Cannot be determined from the information given. 
A)  salt water 
B)  fresh water 
C)  Buoyant force is the same in both. 
D)  Cannot be determined from the information given.

Question 2

A 12,000-N car is raised using a hydraulic lift, which consists of a U-tube with arms of unequal areas, filled with oil with a density of 800 kg/m3 and capped at both ends with tight-fitting pistons. The wider arm of the U-tube has a radius of 18.0 cm and the narrower arm has a radius of 5.00 cm. The car rests on the piston on the wider arm of the U-tube. The pistons are initially at the same level. What is the force that must be applied to the smaller piston in order to lift the car after it has been raised 1.20 m? For purposes of this problem, neglect the weight of the pistons.

Accepted Answer

A)  0.954 kN 
B)  1.88 kN 
C)  1.96 kN 
D)  3.67 kN 
E)  1.20 kN 
A)  0.954 kN 
B)  1.88 kN 
C)  1.96 kN 
D)  3.67 kN 
E)  1.20 kN

Question 3

The Aswan High Dam is 111 m high. What is the water pressure at the foot of the dam?

Accepted Answer

A)  1.09 × 106 Pa 
B)  1.16 × 106 Pa 
C)  1.09 × 103 Pa 
D)  1.11 × 105 Pa 
E)  1.11 × 102 Pa 
A)  1.09 × 106 Pa 
B)  1.16 × 106 Pa 
C)  1.09 × 103 Pa 
D)  1.11 × 105 Pa 
E)  1.11 × 102 Pa

Question 4

What is meant by gauge pressure?

Accepted Answer

It is the difference

Question 5

An object floats on a fluid if its density is less than that of the fluid.

Accepted Answer

A) True 
 B)False

Question 6

Atmospheric pressure is approximately

Accepted Answer

A)  1.01 × 102 Pa 
B)  1.01 × 103 Pa 
C)  1.01 × 104 Pa 
D)  1.01 × 105 Pa 
E)  1.01 × 106 Pa 
A)  1.01 × 102 Pa 
B)  1.01 × 103 Pa 
C)  1.01 × 104 Pa 
D)  1.01 × 105 Pa 
E)  1.01 × 106 Pa

Question 7

A person weighting 700 N stands in the middle of an otherwise empty 4 m x 5 m x 3 m room. How does the weight of the person compare with the weight of the air (the density of air is 1.29 kg/m3) in the room?

Accepted Answer

A)  The weight of the air is much more than the weight of the person. 
B)  The weight of the air is about the same as the weight of the person. 
C)  The weight of the air is much less than the weight of the person. 
D)  It makes no sense to speak of weight for a gas like air. 
A)  The weight of the air is much more than the weight of the person. 
B)  The weight of the air is about the same as the weight of the person. 
C)  The weight of the air is much less than the weight of the person. 
D)  It makes no sense to speak of weight for a gas like air.

Question 8

An airplane is flying in air with a density of 1.29 kg/m3. A pressure gauge measures the difference in pressure between a point on the nose of the airplane and a point on the fuselage. The pressure on the nose is higher by 60.0 kPa. What is the speed of the plane relative to the air?

Accepted Answer

A)  295 m/s 
B)  300 m/s 
C)  305 m/s 
D)  310 m/s 
E)  315 m/s 
A)  295 m/s 
B)  300 m/s 
C)  305 m/s 
D)  310 m/s 
E)  315 m/s

Question 9

What is the difference between the pressures inside and outside a tire called?

Accepted Answer

A)  absolute pressure 
B)  atmospheric pressure 
C)  fluid pressure 
D)  gauge pressure 
E)  N/m2 
A)  absolute pressure 
B)  atmospheric pressure 
C)  fluid pressure 
D)  gauge pressure 
E)  N/m2

Question 10

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)  176 m/s 
B)  29.3 m/s 
C)  88.0 m/s 
D)  35.2 m/s 
E)  343 m/s 
A)  176 m/s 
B)  29.3 m/s 
C)  88.0 m/s 
D)  35.2 m/s 
E)  343 m/s

Question 11

FIGURE 15-3  
-The U-tube shown in Figure 15-3 contains mercury with a density of 13,600 kg/m3. It is open on one end and the other end is connected to a boiler, which contains water at high pressure. The water from the boiler pushes directly on the mercury column. What is the gauge pressure at point A in the boiler?

Accepted Answer

A)  4.54 kPa 
B)  4.41 kPa 
C)  128 Pa 
D)  441 Pa 
E)  449 Pa 
A)  4.54 kPa 
B)  4.41 kPa 
C)  128 Pa 
D)  441 Pa 
E)  449 Pa

Question 12

Bernoulli's principle is a statement of the

Accepted Answer

A)  conservation of linear momentum. 
B)  conservation of mass. 
C)  conservation of energy. 
D)  conservation of kinetic energy. 
E)  conservation of angular momentum. 
A)  conservation of linear momentum. 
B)  conservation of mass. 
C)  conservation of energy. 
D)  conservation of kinetic energy. 
E)  conservation of angular momentum.

Question 13

FIGURE 15-11  
-Water flows in the horizontal pipe shown in Figure 15-11. At A the diameter is 6.00 cm and at B the diameter is 5.00 cm. The fluid in the manometer is oil, which has a density of 800 kg/m3. The manometer reading h is 10.0 cm. What is the speed of the water at B?

Accepted Answer

A)  0.195 m/s 
B)  1.55 m/s 
C)  1.74 m/s 
D)  8.70 m/s 
E)  11.4 m/s 
A)  0.195 m/s 
B)  1.55 m/s 
C)  1.74 m/s 
D)  8.70 m/s 
E)  11.4 m/s

Question 14

FIGURE 15-17  
-Water flows over the overflow structure shown in Figure 15-17. The depth of water upstream is 2.00 m and downstream it is 50.0 cm. What volume of water flows over the structure per second per meter of width?

Accepted Answer

A)  2.80 m3/s/m 
B)  1.40 m3/s/m 
C)  5.60 m3/s/m 
D)  3.40 m3/s/m 
E)  0.700 m3/s/m 
A)  2.80 m3/s/m 
B)  1.40 m3/s/m 
C)  5.60 m3/s/m 
D)  3.40 m3/s/m 
E)  0.700 m3/s/m

Question 15

When soup gets cold, it often tastes greasy. This "greasy" taste seems to be associated with oil spreading out all over the surface of the soup, instead of staying in little globules. This is readily explained in terms of

Accepted Answer

A)  the Bernoulli effect. 
B)  Archimedes Principle. 
C)  Pascal's Principle. 
D)  the decrease in the surface tension of water with increasing temperature. 
E)  the increase in the surface tension of water with increasing temperature. 
A)  the Bernoulli effect. 
B)  Archimedes Principle. 
C)  Pascal's Principle. 
D)  the decrease in the surface tension of water with increasing temperature. 
E)  the increase in the surface tension of water with increasing temperature.

Question 16

FIGURE 15-18  
-Water flows through the 30.0-cm diameter pipe shown in Figure 15-18. An open tube is flush with an opening in the pipe at A and enters the pipe at B and is bent along the centerline of the pipe to face the oncoming flow, as shown in the figure. Water enters the tube and rises until the hydrostatic pressure in the tube balances the pressure at the mouth of the tube. Because no more water enters the tube, the speed of the water just outside the mouth of the tube is zero m/s. What is the speed of the water in the pipe if the manometer reading is 8.50 cm? The manometer fluid is oil with a density of 800 kg/m3.

Accepted Answer

A)  0.125 m/s 
B)  0.323 m/s 
C)  0.424 m/s 
D)  0.525 m/s 
E)  0.577 m/s 
A)  0.125 m/s 
B)  0.323 m/s 
C)  0.424 m/s 
D)  0.525 m/s 
E)  0.577 m/s

Question 17

FIGURE 15-10  
-Water flows in the horizontal pipe shown in Figure 15-10. At A the diameter is 5.00 cm and at B the diameter is 4.00 cm. The fluid in the manometer is mercury, which has a density of 13,600 kg/m3. The manometer reading h is 3.60 cm. What volume of water is flowing through the pipe per second?

Accepted Answer

A)  0.0206 m3/s 
B)  0.0426 m3/s 
C)  0.00507 m3/s 
D)  0.372 m3/s 
E)  0.186 m3/s 
A)  0.0206 m3/s 
B)  0.0426 m3/s 
C)  0.00507 m3/s 
D)  0.372 m3/s 
E)  0.186 m3/s

Question 18

Water is flowing in a drainage channel of rectangular cross-section. At one point, the width of the channel is 12 m, the depth of water is 6.0 m, and the speed of the flow is 2.5 m/s. At a point downstream, the width has narrowed to 9.0 m, and the depth of water is 8.0 m. What is the speed of the flow at the second point?

Accepted Answer

A)  2.0 m/s 
B)  2.5 m/s 
C)  3.0 m/s 
D)  3.5 m/s 
E)  4.0 m/s 
A)  2.0 m/s 
B)  2.5 m/s 
C)  3.0 m/s 
D)  3.5 m/s 
E)  4.0 m/s

Question 19

A barge is 10.0 m wide and 60.0 m long and has vertical sides. The bottom of the hull is 1.20 m below the water surface. What is the weight of the barge and its cargo, if it is floating in fresh water?

Accepted Answer

A)  3.53 MN 
B)  6.39 MN 
C)  6.82 MN 
D)  7.06 MN 
E)  9.54 MN 
A)  3.53 MN 
B)  6.39 MN 
C)  6.82 MN 
D)  7.06 MN 
E)  9.54 MN

Question 20

The pressure differential across a wing cross section due to the difference in air flow is explained by

Accepted Answer

A)  Pascal's Principle. 
B)  Bernoulli's equation. 
C)  Poiseuille's law. 
D)  Archimedes Principle. 
E)  Torricelli's law. 
A)  Pascal's Principle. 
B)  Bernoulli's equation. 
C)  Poiseuille's law. 
D)  Archimedes Principle. 
E)  Torricelli's law.

Exam 15: Fluids

Salt water has greater density than fresh water. A boat floats in both fresh water and in salt water. Where is the buoyant force greater on the boat?

The Aswan High Dam is 111 m high. What is the water pressure at the foot of the dam?

What is meant by gauge pressure?

An object floats on a fluid if its density is less than that of the fluid.

Atmospheric pressure is approximately

A person weighting 700 N stands in the middle of an otherwise empty 4 m x 5 m x 3 m room. How does the weight of the person compare with the weight of the air (the density of air is 1.29 kg/m3) in the room?

An airplane is flying in air with a density of 1.29 kg/m3. A pressure gauge measures the difference in pressure between a point on the nose of the airplane and a point on the fuselage. The pressure on the nose is higher by 60.0 kPa. What is the speed of the plane relative to the air?

What is the difference between the pressures inside and outside a tire called?

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?

Bernoulli's principle is a statement of the

FIGURE 15-11 -Water flows in the horizontal pipe shown in Figure 15-11. At A the diameter is 6.00 cm and at B the diameter is 5.00 cm. The fluid in the manometer is oil, which has a density of 800 kg/m3. The manometer reading h is 10.0 cm. What is the speed of the water at B?

FIGURE 15-17 -Water flows over the overflow structure shown in Figure 15-17. The depth of water upstream is 2.00 m and downstream it is 50.0 cm. What volume of water flows over the structure per second per meter of width?

When soup gets cold, it often tastes greasy. This "greasy" taste seems to be associated with oil spreading out all over the surface of the soup, instead of staying in little globules. This is readily explained in terms of

A barge is 10.0 m wide and 60.0 m long and has vertical sides. The bottom of the hull is 1.20 m below the water surface. What is the weight of the barge and its cargo, if it is floating in fresh water?

The pressure differential across a wing cross section due to the difference in air flow is explained by

Introduction to Physics

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A person weighting 700 N stands in the middle of an otherwise empty 4 m x 5 m x 3 m room. How does the weight of the person compare with the weight of the air (the density of air is 1.29 kg/m³) in the room?

An airplane is flying in air with a density of 1.29 kg/m³. A pressure gauge measures the difference in pressure between a point on the nose of the airplane and a point on the fuselage. The pressure on the nose is higher by 60.0 kPa. What is the speed of the plane relative to the air?

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?

FIGURE 15-11 -Water flows in the horizontal pipe shown in Figure 15-11. At A the diameter is 6.00 cm and at B the diameter is 5.00 cm. The fluid in the manometer is oil, which has a density of 800 kg/m³. The manometer reading h is 10.0 cm. What is the speed of the water at B?