Question 1

A 50-cm3 block of wood is floating partially submerged in water, and a 50-cm3 block of iron is totally submerged in water. Which block has the greater buoyant force on it?

Accepted Answer

A)  the wood 
B)  the iron 
C)  Both have the same buoyant force. 
D)  The answer cannot be determined without knowing the densities of the blocks. 
A)  the wood 
B)  the iron 
C)  Both have the same buoyant force. 
D)  The answer cannot be determined without knowing the densities of the blocks. B

Question 2

A board that is 20.0 cm wide, 5.00 cm thick, and 3.00 m long has a density 350 kg/m3. The board is floating partially submerged in water of density 1000 kg/m3. What fraction of the volume of the board is above the surface of the water?

Accepted Answer

A)  0.350 
B)  0.650 
C)  zero 
D)  0.200 
E)  The answer depends on which edge of the board is vertical. 
A)  0.350 
B)  0.650 
C)  zero 
D)  0.200 
E)  The answer depends on which edge of the board is vertical. B

Question 3

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 
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 C

Question 4

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. 
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

A level pipe contains a nonviscous, incompressible fluid with a density 1200 kg/m3 that is flowing steadily. At one position within the pipe, the pressure is 300 kPa and the speed of the flow is 20.0 m/s. At another position, the pressure is 200 kPa. What is the speed of the flow at this second position?

Accepted Answer

A)  567 m/s 
B)  16.2 m/s 
C)  32.9 m/s 
D)  23.8 m/s 
E)  186 m/s 
A)  567 m/s 
B)  16.2 m/s 
C)  32.9 m/s 
D)  23.8 m/s 
E)  186 m/s

Question 6

Water is flowing in a horizontal pipe of diameter d. If you want to change the diameter of this pipe so that the speed of the water would be half as great as it was, what should be the new diameter?

Accepted Answer

A)  d/4 
B)  d/2 
C)  d /   
D)  d   
E)  2d 
A)  d/4 
B)  d/2 
C)  d /   
D)  d   
E)  2d

Question 7

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

Question 8

A rock is suspended from a scale reads 20.0 N. A beaker of water (having a density of 1000 kg/m3) is raised up so the rock is totally submerged in the water. The scale now reads 12.5 N. What is the density of the rock?

Accepted Answer

A)  1.60 × 103 kg/m3 
B)  2.50 × 103 kg/m3 
C)  2.33 × 103 kg/m3 
D)  3.00 × 103 kg/m3 
E)  2.67 × 103 kg/m3 
A)  1.60 × 103 kg/m3 
B)  2.50 × 103 kg/m3 
C)  2.33 × 103 kg/m3 
D)  3.00 × 103 kg/m3 
E)  2.67 × 103 kg/m3

Question 9

In the figure, an open tank contains a layer of oil floating on top of a layer of water (of density 1000 kg/m3) that is 3.0 m thick, as shown. What must be the thickness of the oil layer if the gauge pressure at the bottom of the tank is to be 5.0 × 104 Pa? The density of the oil is 510 kg/m3.

Accepted Answer

Question 10

Water flowing through a pipe suddenly comes to a section of pipe where the pipe diameter decreases to 86% of its previous value. If the speed of the water in the larger section of the pipe was 36m/s, what is its speed in this smaller section?

Accepted Answer

A)  49 m/s 
B)  42 m/s 
C)  31 m/s 
D)  27 m/s 
A)  49 m/s 
B)  42 m/s 
C)  31 m/s 
D)  27 m/s

Question 11

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

Question 12

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

Question 13

Water flows in the horizontal pipe shown in the figure. 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 4.40 cm. We can treat water as an ideal fluid having a density of 1000 kg/m3. What volume of water is flowing through the pipe per second?

Accepted Answer

A)  0.0206 m3/s 
B)  0.0426 m3/s 
C)  0.00560 m3/s 
D)  0.372 m3/s 
E)  0.186 m3/s 
A)  0.0206 m3/s 
B)  0.0426 m3/s 
C)  0.00560 m3/s 
D)  0.372 m3/s 
E)  0.186 m3/s

Question 14

What is the radius of a sphere that has a density of 5000 kg/m3 and a mass of 6.00 kg?

Accepted Answer

A)  4.98 cm 
B)  1.27 cm 
C)  6.59 cm 
D)  1.56 cm 
E)  7.22 cm 
A)  4.98 cm 
B)  1.27 cm 
C)  6.59 cm 
D)  1.56 cm 
E)  7.22 cm

Question 15

A 7.8-kg solid sphere, made of metal whose density is 2500 kg/m3, is suspended by a cord. When the sphere is immersed in water (of density 1000 kg/m3), what is the tension in the cord?

Accepted Answer

A)  46 N 
B)  61 N 
C)  76 N 
D)  92 N 
E)  110 N 
A)  46 N 
B)  61 N 
C)  76 N 
D)  92 N 
E)  110 N

Question 16

A 6.1-kg solid sphere, made of metal whose density is 2600 kg/ m3, is suspended by a cord. When the sphere is immersed in a liquid of unknown density, the tension in the cord is 26 N. Find the density of the liquid.

Accepted Answer

A)  1500 kg/m3 
B)  1400 kg/m3 
C)  1300 kg/m3 
D)  1200 kg/m3 
E)  1100 kg/m3 
A)  1500 kg/m3 
B)  1400 kg/m3 
C)  1300 kg/m3 
D)  1200 kg/m3 
E)  1100 kg/m3

Question 17

The small piston of a hydraulic lift has a diameter of 8.0 cm, and its large piston has a diameter of 40 cm. The lift raises a load of 15,000 N.
(a) Determine the force that must be applied to the small piston.
(b) Determine the pressure applied to the fluid in the lift.

Accepted Answer

(a) 600 N

Question 18

A hollow steel ball of diameter 3.0 m barely floats in water. What is the thickness of the wall of the ball? The density of iron is 7.87 g/cm3 and that of water is 1000 kg/m3.

Accepted Answer

A)  6.6 cm 
B)  37 cm 
C)  131 cm 
D)  79 cm 
A)  6.6 cm 
B)  37 cm 
C)  131 cm 
D)  79 cm

Question 19

A circular cylinder of height 1.20 m having faces of diameter 0.620 m is immersed in water of density 1.00 × 103 kg/m3 with its axis vertical so that its faces are parallel to the surface of the water. The upper face is 2.50 m below the surface of the water. The net force on this cylinder is observed to be 1120 N downward. Atmospheric pressure is 1.01 × 105 Pa. What is the weight of the cylinder?

Accepted Answer

A)  2430 N 
B)  3550 N 
C)  4670 N 
D)  10,900 N 
E)  12,100 N 
A)  2430 N 
B)  3550 N 
C)  4670 N 
D)  10,900 N 
E)  12,100 N

Question 20

A paint sprayer pumps air through a constriction in a 2.50-cm diameter pipe, as shown in the figure. The flow causes the pressure in the constricted area to drop and paint rises up the feed tube and enters the air stream. The speed of the air stream in the 2.50-cm diameter sections is 5.00 m/s. The density of the air is 1.29 kg/m3, and the density of the paint is 1200 kg/m3. We can treat the air and paint as incompressible ideal fluids. What is the maximum diameter of the constriction that will allow the sprayer to operate?

Accepted Answer

A)  8.07 mm 
B)  4.05 mm 
C)  12.2 mm 
D)  9.65 mm 
E)  14.3 mm 
A)  8.07 mm 
B)  4.05 mm 
C)  12.2 mm 
D)  9.65 mm 
E)  14.3 mm

Exam 11: Fluid Mechanics

A 50-cm3 block of wood is floating partially submerged in water, and a 50-cm3 block of iron is totally submerged in water. Which block has the greater buoyant force on it?

A board that is 20.0 cm wide, 5.00 cm thick, and 3.00 m long has a density 350 kg/m3. The board is floating partially submerged in water of density 1000 kg/m3. What fraction of the volume of the board is above the surface of the water?

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?

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

Water is flowing in a horizontal pipe of diameter d. If you want to change the diameter of this pipe so that the speed of the water would be half as great as it was, what should be the new diameter?

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?

A rock is suspended from a scale reads 20.0 N. A beaker of water (having a density of 1000 kg/m3) is raised up so the rock is totally submerged in the water. The scale now reads 12.5 N. What is the density of the rock?

In the figure, an open tank contains a layer of oil floating on top of a layer of water (of density 1000 kg/m3) that is 3.0 m thick, as shown. What must be the thickness of the oil layer if the gauge pressure at the bottom of the tank is to be 5.0 × 104 Pa? The density of the oil is 510 kg/m3.

Water flowing through a pipe suddenly comes to a section of pipe where the pipe diameter decreases to 86% of its previous value. If the speed of the water in the larger section of the pipe was 36m/s, what is its speed in this smaller section?

As the speed of a moving fluid increases, the pressure in the fluid

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?

What is the radius of a sphere that has a density of 5000 kg/m3 and a mass of 6.00 kg?

A 7.8-kg solid sphere, made of metal whose density is 2500 kg/m3, is suspended by a cord. When the sphere is immersed in water (of density 1000 kg/m3), what is the tension in the cord?

A 6.1-kg solid sphere, made of metal whose density is 2600 kg/ m3, is suspended by a cord. When the sphere is immersed in a liquid of unknown density, the tension in the cord is 26 N. Find the density of the liquid.

The small piston of a hydraulic lift has a diameter of 8.0 cm, and its large piston has a diameter of 40 cm. The lift raises a load of 15,000 N. (a) Determine the force that must be applied to the small piston. (b) Determine the pressure applied to the fluid in the lift.

A hollow steel ball of diameter 3.0 m barely floats in water. What is the thickness of the wall of the ball? The density of iron is 7.87 g/cm3 and that of water is 1000 kg/m3.

Units, Physical Quantities, and Vectors

Motion Along a Straight Line

Motion in Two or Three Dimensions

Newtons Laws of Motion

Applying Newtons Laws

Work and Kinetic Energy

Potential Energy and Energy Conservation

Momentum, Impulse, and Collisions

Rotation of Rigid Bodies

Equilibrium and Elasticity

Gravitation

Periodic Motion

Mechanical Waves

Sound and Hearing

Temperature and Heat

Thermal Properties of Matter

The First Law of Thermodynamics

The Second Law of Thermodynamics

Electric Charge and Electric Field

Gausss Law

Electric Potential

Capacitance and Dielectrics

Current, Resistance, and Electromotive Force

Direct-Current Circuits

Magnetic Field and Magnetic Forces

Sources of Magnetic Field

Electromagnetic Induction

Inductance

Alternating Current

Electromagnetic Waves

The Nature and Propagation of Light

Geometric Optics

Interference

Diffraction

Relativity

Photons: Light Waves Behaving As Particles

Particles Behaving As Waves

Quantum Mechanics

Atomic Structure

Molecules and Condensed Matter

Nuclear Physics

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Filters

A 50-cm³ block of wood is floating partially submerged in water, and a 50-cm³ block of iron is totally submerged in water. Which block has the greater buoyant force on it?

A board that is 20.0 cm wide, 5.00 cm thick, and 3.00 m long has a density 350 kg/m³. The board is floating partially submerged in water of density 1000 kg/m³. What fraction of the volume of the board is above the surface of the water?

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?

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?

A rock is suspended from a scale reads 20.0 N. A beaker of water (having a density of 1000 kg/m³) is raised up so the rock is totally submerged in the water. The scale now reads 12.5 N. What is the density of the rock?

In the figure, an open tank contains a layer of oil floating on top of a layer of water (of density 1000 kg/m³) that is 3.0 m thick, as shown. What must be the thickness of the oil layer if the gauge pressure at the bottom of the tank is to be 5.0 × 10⁴ Pa? The density of the oil is 510 kg/m³.

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?

What is the radius of a sphere that has a density of 5000 kg/m³ and a mass of 6.00 kg?

A 7.8-kg solid sphere, made of metal whose density is 2500 kg/m³, is suspended by a cord. When the sphere is immersed in water (of density 1000 kg/m³), what is the tension in the cord?

A 6.1-kg solid sphere, made of metal whose density is 2600 kg/ m³, is suspended by a cord. When the sphere is immersed in a liquid of unknown density, the tension in the cord is 26 N. Find the density of the liquid.

A hollow steel ball of diameter 3.0 m barely floats in water. What is the thickness of the wall of the ball? The density of iron is 7.87 g/cm³ and that of water is 1000 kg/m³.