Question 1

Under standard conditions, the density of air is 1.29 kg/m3. What is the mass of the air inside a room measuring 4.0 m × 3.0 m × 2.0 m?

Accepted Answer

A)  0.32 kg 
B)  3.1 kg 
C)  31 kg 
D)  1.9 kg 
E)  19 kg 
A)  0.32 kg 
B)  3.1 kg 
C)  31 kg 
D)  1.9 kg 
E)  19 kg

Question 2

A cubical block of stone is lowered at a steady rate into the ocean by a crane, always keeping the top and bottom faces horizontal. Which one of the following graphs best describes the gauge pressure p on the bottom of this block as a function of time t if the block just enters the water at time t = 0 s?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  
B) 
  
C) 
  
D) 
  
E)

Question 3

In a hydraulic garage lift, the small piston has a radius of 5.0 cm and the large piston has a radius of 15 cm. What force must be applied on the small piston in order to lift a car weighing 20,000 N on the large piston? Assume the pistons each have negligible weight.

Accepted Answer

A)  6.7 × 103 N 
B)  5.0 × 103 N 
C)  2.9 × 103 N 
D)  2.2 × 103 N 
A)  6.7 × 103 N 
B)  5.0 × 103 N 
C)  2.9 × 103 N 
D)  2.2 × 103 N

Question 4

A compressed gas with a total mass of $107 \mathrm {~kg}$ is stored in a spherical container having a radius of 0.521 m. What is the density of the compressed gas?

Accepted Answer

A)  181 kg/m3 
B)  110 kg/m3 
C)  134 kg/m3 
D)  161 kg/m3 
A)  181 kg/m3 
B)  110 kg/m3 
C)  134 kg/m3 
D)  161 kg/m3

Question 5

A cubical box 25.0 cm on each side is immersed in a fluid. The pressure at the top surface of the box is 109.40 kPa and the pressure on the bottom surface is 112.00 kPa. What is the density of the fluid?

Accepted Answer

A)  1000 kg/m3 
B)  1030 kg/m3 
C)  1060 kg/m3 
D)  1090 kg/m3 
E)  1120 kg/m3 
A)  1000 kg/m3 
B)  1030 kg/m3 
C)  1060 kg/m3 
D)  1090 kg/m3 
E)  1120 kg/m3

Question 6

As shown in the figure, a large open tank contains a layer of oil ( density 450 kg/ $m ^ { 3 }$ ) floating on top of a layer of water (density 1000 kg/m3) that is 3.0 m thick, as shown in the sketch. What must be the thickness of the oil layer if the gauge pressure at the bottom of the tank is to be $8.5 \times 10^4 \mathrm {~Pa} ?$

Accepted Answer

Question 7

A rectangular wooden block measures 10.0 cm × 4.00 cm × 2.00 cm. When the block is placed in water, it floats horizontally, with its bottom face 1.65 cm below the surface. What is the density of the wood? The density of water is 1.00 g/cm3.

Accepted Answer

A)  0.825 g/cm3 
B)  1.21 g/cm3 
C)  1.65 g/cm3 
D)  0.606 g/cm3 
E)  0.350 g/cm3 
A)  0.825 g/cm3 
B)  1.21 g/cm3 
C)  1.65 g/cm3 
D)  0.606 g/cm3 
E)  0.350 g/cm3

Question 8

Fluid flows at 2.0 m/s through a pipe of diameter 3.0 cm. What is the volume flow rate of the fluid?

Accepted Answer

A)  1.4 × 10-3 m3/s 
B)  5.7 × 10-3 m3/s 
C)  14 m3/s 
D)  57 m3/s 
A)  1.4 × 10-3 m3/s 
B)  5.7 × 10-3 m3/s 
C)  14 m3/s 
D)  57 m3/s

Question 9

A hollow sphere of negligible mass and radius R is completely filled with a liquid so that its density is ρ. You now enlarge the sphere so its radius is 2R and completely fill it with the same liquid. What is the density of the enlarged sphere?

Accepted Answer

A)  8 ρ 
B)  4 ρ 
C)  ρ/2 
D)  ρ 
E)  ρ/8 
A)  8 ρ 
B)  4 ρ 
C)  ρ/2 
D)  ρ 
E)  ρ/8

Question 10

Motor oil, with a viscosity of 0.25 N ∙ s/m2, is flowing through a tube that has a radius of 3.0 mm and is 1.0 m long. The drop in pressure over the length of the tube is 200 kPa. What is the average speed of the oil?

Accepted Answer

A)  0.80 m/s 
B)  0.90 m/s 
C)  1.0 m/s 
D)  1.1 m/s 
E)  1.2 m/s 
A)  0.80 m/s 
B)  0.90 m/s 
C)  1.0 m/s 
D)  1.1 m/s 
E)  1.2 m/s

Question 11

A water tank is filled to a depth of 10 m, and the bottom of the tank is 20 m above ground. A water-filled hose that is 2.0 cm in diameter extends from the bottom of the tank to the ground, but no water is flowing in this hose. The water pressure at ground level in the hose is closest to which of the following values? The density of water is 1000 kg/m3.

Accepted Answer

A)  3.9 × 105 N/m2 
B)  2.0 × 104 N/m2 
C)  9.2 N/m2 
D)  The question cannot be answered because the cross sectional area of the tank is needed. 
A)  3.9 × 105 N/m2 
B)  2.0 × 104 N/m2 
C)  9.2 N/m2 
D)  The question cannot be answered because the cross sectional area of the tank is needed.

Question 12

What force does the water exert (in addition to that due to atmospheric pressure) on a submarine window of radius 44.0 cm at a depth of 9400 m in sea water? The density of sea water is 1025 kg/m3.

Accepted Answer

A)  5.74 × 107 N  
B)  5.74 × 1011 N 
C)  2.87 × 1011 N 
D)  1.83 × 107 N 
E)  2.87 × 107 N 
A)  5.74 × 107 N  
B)  5.74 × 1011 N 
C)  2.87 × 1011 N 
D)  1.83 × 107 N 
E)  2.87 × 107 N

Question 13

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)  in salt water 
B)  in fresh water 
C)  The buoyant force is the same in both cases. 
A)  in salt water 
B)  in fresh water 
C)  The buoyant force is the same in both cases.

Question 14

A styrofoam sphere of radius R has a density ρ. You now carefully compress the sphere so its radius is R/2. What is the density of the compressed sphere?

Accepted Answer

A)  2 ρ 
B)  4 ρ 
C)  ρ $\sqrt { 8 }$ 
D)  ρ $\sqrt { 2 }$ 
E)  8 ρ 
A)  2 ρ 
B)  4 ρ 
C)  ρ $\sqrt { 8 }$ 
D)  ρ $\sqrt { 2 }$ 
E)  8 ρ

Question 15

For a certain patient, the build-up of fatty tissue on the wall of an artery has decreased the arterial radius by 10%. By how much would the pressure provided by the heart have to be increased to maintain a constant volume of blood flow? Model the blood as an ideal incompressible fluid.

Accepted Answer

A)  48% 
B)  52% 
C)  46% 
D)  54% 
A)  48% 
B)  52% 
C)  46% 
D)  54%

Question 16

What buoyant force does a 0.60-kg solid gold crown experience when it is immersed in water? The density of gold is 19.3 × 103 kg/m3 and that of water is 1000 kg/m3.

Accepted Answer

A)  3.0 × 10-5 N 
B)  3.0 × 10-4 N 
C)  3.0 × 10-2 N 
D)  0.30 N 
A)  3.0 × 10-5 N 
B)  3.0 × 10-4 N 
C)  3.0 × 10-2 N 
D)  0.30 N

Question 17

Motor oil, with a viscosity of 0.25 N ∙ s/m2, is flowing through a tube that has a radius of 5.0 mm and is 25 cm long. The drop in pressure is 300 kPa. What is the volume of oil flowing through the tube per second?

Accepted Answer

A)  0.00038 m3/s 
B)  0.025 m3/s 
C)  0.0012 m3/s 
D)  4.7 m3/s 
E)  7.5 m3/s 
A)  0.00038 m3/s 
B)  0.025 m3/s 
C)  0.0012 m3/s 
D)  4.7 m3/s 
E)  7.5 m3/s

Question 18

As shown in the figure, water (density 1000 kg/ $m ^ { 3 }$ ) is flowing in a pipeline. At point 1 the water speed is $5.90 \mathrm {~m} / \mathrm { s }$ Point 2 is 5.20 m above point 1. The cross-sectional area of the pipe is 0.0800 $m ^ { 2 }$ at point 1 and $0.0200 \mathrm {~m} ^ { 2 }$ at point 2. What is the pressure difference $p 1 - p 2$ between points 1 and 2? Treat the water as an ideal incompressible fluid.

Accepted Answer

The answer of As shown in the figure, water (density...

Question 19

Water flowing through a cylindrical pipe suddenly comes to a section of pipe where the diameter decreases to 86% of its previous value. If the speed of the water in the larger section of the pipe was $32 \mathrm {~m} / \mathrm { s }$ what is its speed in this smaller section if the water behaves like an ideal incompressible fluid?

Accepted Answer

A)  43 m/s 
B)  37 m/s 
C)  28 m/s 
D)  24 m/s 
A)  43 m/s 
B)  37 m/s 
C)  28 m/s 
D)  24 m/s

Question 20

A container has a vertical tube, whose inner radius is 20.00 mm, connected to it at its side, as shown in the figure. An unknown liquid reaches level A in the container and level B in the tube-level A being 5.0 cm higher than level B. The liquid supports a 20-cm high column of oil, between levels B and C, whose density is $900 \mathrm {~kg} / \mathrm { m } ^ { 3 }$ The density of the unknown liquid is closest to

Accepted Answer

A)  3600 kg/ $m ^ { 3 }$ 
B)  3900 kg/ $m ^ { 3 }$ 
C)  2800 kg/ $m ^ { 3 }$ 
D)  3100 kg/ $m ^ { 3 }$ 
E)  3300 kg/ $m ^ { 3 }$ 
A)  3600 kg/ $m ^ { 3 }$ 
B)  3900 kg/ $m ^ { 3 }$ 
C)  2800 kg/ $m ^ { 3 }$ 
D)  3100 kg/ $m ^ { 3 }$ 
E)  3300 kg/ $m ^ { 3 }$

Exam 13: Fluids

Under standard conditions, the density of air is 1.29 kg/m3. What is the mass of the air inside a room measuring 4.0 m × 3.0 m × 2.0 m?

In a hydraulic garage lift, the small piston has a radius of 5.0 cm and the large piston has a radius of 15 cm. What force must be applied on the small piston in order to lift a car weighing 20,000 N on the large piston? Assume the pistons each have negligible weight.

A compressed gas with a total mass of 107 kg107 \mathrm {~kg}107 kg is stored in a spherical container having a radius of 0.521 m. What is the density of the compressed gas?

A cubical box 25.0 cm on each side is immersed in a fluid. The pressure at the top surface of the box is 109.40 kPa and the pressure on the bottom surface is 112.00 kPa. What is the density of the fluid?

A rectangular wooden block measures 10.0 cm × 4.00 cm × 2.00 cm. When the block is placed in water, it floats horizontally, with its bottom face 1.65 cm below the surface. What is the density of the wood? The density of water is 1.00 g/cm3.

Fluid flows at 2.0 m/s through a pipe of diameter 3.0 cm. What is the volume flow rate of the fluid?

A hollow sphere of negligible mass and radius R is completely filled with a liquid so that its density is ρ. You now enlarge the sphere so its radius is 2R and completely fill it with the same liquid. What is the density of the enlarged sphere?

Motor oil, with a viscosity of 0.25 N ∙ s/m2, is flowing through a tube that has a radius of 3.0 mm and is 1.0 m long. The drop in pressure over the length of the tube is 200 kPa. What is the average speed of the oil?

What force does the water exert (in addition to that due to atmospheric pressure) on a submarine window of radius 44.0 cm at a depth of 9400 m in sea water? The density of sea water is 1025 kg/m3.

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?

A styrofoam sphere of radius R has a density ρ. You now carefully compress the sphere so its radius is R/2. What is the density of the compressed sphere?

For a certain patient, the build-up of fatty tissue on the wall of an artery has decreased the arterial radius by 10%. By how much would the pressure provided by the heart have to be increased to maintain a constant volume of blood flow? Model the blood as an ideal incompressible fluid.

What buoyant force does a 0.60-kg solid gold crown experience when it is immersed in water? The density of gold is 19.3 × 103 kg/m3 and that of water is 1000 kg/m3.

Motor oil, with a viscosity of 0.25 N ∙ s/m2, is flowing through a tube that has a radius of 5.0 mm and is 25 cm long. The drop in pressure is 300 kPa. What is the volume of oil flowing through the tube per second?

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Under standard conditions, the density of air is 1.29 kg/m³. What is the mass of the air inside a room measuring 4.0 m × 3.0 m × 2.0 m?

A compressed gas with a total mass of $107 \mathrm {~kg}$ is stored in a spherical container having a radius of 0.521 m. What is the density of the compressed gas?

A rectangular wooden block measures 10.0 cm × 4.00 cm × 2.00 cm. When the block is placed in water, it floats horizontally, with its bottom face 1.65 cm below the surface. What is the density of the wood? The density of water is 1.00 g/cm³.

Motor oil, with a viscosity of 0.25 N ∙ s/m², is flowing through a tube that has a radius of 3.0 mm and is 1.0 m long. The drop in pressure over the length of the tube is 200 kPa. What is the average speed of the oil?

What force does the water exert (in addition to that due to atmospheric pressure) on a submarine window of radius 44.0 cm at a depth of 9400 m in sea water? The density of sea water is 1025 kg/m³.

What buoyant force does a 0.60-kg solid gold crown experience when it is immersed in water? The density of gold is 19.3 × 10³ kg/m³ and that of water is 1000 kg/m³.

Motor oil, with a viscosity of 0.25 N ∙ s/m², is flowing through a tube that has a radius of 5.0 mm and is 25 cm long. The drop in pressure is 300 kPa. What is the volume of oil flowing through the tube per second?