Question 1

You are driving a late model convertible car at the 65 mph speed limit with its soft flexible roof closed up and the windows closed.You observe that the roof

Accepted Answer

A)  bows inward. 
B)  is no different from when the car was at rest. 
C)  bows outward. 
D)  bows inward only when you are driving uphill. 
E)  bows inward only when you are driving downhill. 
A)  bows inward. 
B)  is no different from when the car was at rest. 
C)  bows outward. 
D)  bows inward only when you are driving uphill. 
E)  bows inward only when you are driving downhill. C

Question 2

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

4.1 m

Question 3

A horizontal tube consists of a 7.0-cm diameter pipe that narrows to a 2.0-cm-diameter throat.In the pipe,the water pressure is twice atmospheric pressure and the water flows with a speed of 0.40 m/s.What is the pressure in the throat,assuming that the water behaves like an ideal fluid? The density of water is 1000 kg/m3,and atmospheric pressure is 1.01 × 105 Pa.

Accepted Answer

A)  1.9 atm 
B)  0.12 atm 
C)  2.1 atm 
D)  2.0 atm 
A)  1.9 atm 
B)  0.12 atm 
C)  2.1 atm 
D)  2.0 atm A

Question 4

A flat horizontal plate of area 400 cm2 is dragged over a 0.20 cm thick layer of oil at a speed of 30.0 cm/s.The oil is resting on a fixed horizontal surface. It takes a force 1.20 N applied to the plate to sustain this speed. What is the viscosity of the oil?

Accepted Answer

A)  6.00 kg/m • s 
B)  20.0 kg/m • s 
C)  60.0 kg/m • s 
D)  0.200 kg/m • s 
E)  200 kg/m • s 
A)  6.00 kg/m • s 
B)  20.0 kg/m • s 
C)  60.0 kg/m • s 
D)  0.200 kg/m • s 
E)  200 kg/m • s

Question 5

On planet X,the absolute pressure at a depth of 2.00 m below the surface of a liquid nitrogen lake is 5.00 × 105 N/m2. At a depth 5.00 m below the surface,the absolute pressure is 8.00 × 105 N/m2. The density of liquid nitrogen is 808 kg/m3.
(a)What is the atmospheric pressure on planet X?
(b)What is the acceleration due to gravity on planet X?

Accepted Answer

(a)3.00 ×

Question 6

A certain coin has a diameter of 21.21 mm,a thickness of 1.95 mm,and weighs 0.04905 N.What is its density?

Accepted Answer

A)  29.1 × 103 kg/m3 
B)  7.26 × 103 kg/m3 
C)  9.25 × 103 kg/m3 
D)  2.31 × 103 kg/m3 
E)  71.2 × 103 kg/m3 
A)  29.1 × 103 kg/m3 
B)  7.26 × 103 kg/m3 
C)  9.25 × 103 kg/m3 
D)  2.31 × 103 kg/m3 
E)  71.2 × 103 kg/m3

Question 7

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 8

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

Question 9

A sphere is constructed of two concentric parts. The inner part is a solid sphere of radius 10.0 cm made of a material with density 4000 kg/m3. The outer part is a spherical shell with inner radius 10.0 cm and outer radius 20.0 cm. The material in the outer shell has a density 9000 kg/m3.
(a)What is the mass of the sphere?
(b)What is the average density of this sphere?

Accepted Answer

(a)281 kg

Question 10

Incompressible water flows out of a large reservoir through a pipe that opens to the atmosphere 5.70 m below the level of the water in the reservoir. What is the speed of the water as it comes out of the pipe?

Accepted Answer

A)  1.72 m/s 
B)  7.47 m/s 
C)  55.8 m/s 
D)  10.6 m/s 
E)  27.9 m/s 
A)  1.72 m/s 
B)  7.47 m/s 
C)  55.8 m/s 
D)  10.6 m/s 
E)  27.9 m/s

Question 11

A cup of water containing an ice cube at 0°C is filled to the brim.The tip of the ice cube sticks out of the surface.As the ice melts,you observe that

Accepted Answer

A)  the cup overflows. 
B)  the cup might overflow but it depends on the actual mass of the ice cube. 
C)  the water level remains the same. 
D)  the water level actually goes down. 
E)  There is not enough information to answer this question. 
A)  the cup overflows. 
B)  the cup might overflow but it depends on the actual mass of the ice cube. 
C)  the water level remains the same. 
D)  the water level actually goes down. 
E)  There is not enough information to answer this question.

Question 12

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.

Question 13

One of the dangers of tornados and hurricanes is the rapid drop in air pressure that is associated with such storms.Assume that the air pressure inside of a sealed house is 1.02 atm when a hurricane hits.The hurricane rapidly decreases the external air pressure to 0.910 atm.A square window in an outside wall of the house measures 2.02 m on each side.What net force (directed outwards)is exerted on this window?
(1 atm = 1.01 × 105 Pa.)

Accepted Answer

A)  4.53 × 104 N 
B)  5.14 × 104 N 
C)  4.78 × 105 N 
D)  5.37 × 105 N 
A)  4.53 × 104 N 
B)  5.14 × 104 N 
C)  4.78 × 105 N 
D)  5.37 × 105 N

Question 14

When you blow some air above the upper face of a paper strip,the paper rises.This occurs because

Accepted Answer

A)  the air above the upper face of the paper moves faster, which makes the pressure higher than at the lower face. 
B)  the air above the upper face of the paper moves faster, which makes the pressure lower than at the lower face. 
C)  the air above the upper face of the paper moves faster but the pressure remains constant. 
D)  the air above the upper face of the paper moves slower, which makes the pressure higher than at the lower face. 
E)  the air above the upper face of the paper moves slower, which makes the pressure lower than at the lower face. 
A)  the air above the upper face of the paper moves faster, which makes the pressure higher than at the lower face. 
B)  the air above the upper face of the paper moves faster, which makes the pressure lower than at the lower face. 
C)  the air above the upper face of the paper moves faster but the pressure remains constant. 
D)  the air above the upper face of the paper moves slower, which makes the pressure higher than at the lower face. 
E)  the air above the upper face of the paper moves slower, which makes the pressure lower than at the lower face.

Question 15

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

Question 16

A wooden raft has a mass of 50 kg.When empty it floats in water (density 1000 kg/m3)with 69% of its volume submerged.What mass of sand can be put on the raft without it sinking?

Accepted Answer

Question 17

The weight of a car of mass 1.20 × 103 kg is supported equally by the four tires,which are inflated to the same gauge pressure.What gauge pressure in the tires is required so the area of contact of each tire with the road is 1.00 × 102 cm2? (1 atm = 1.01 × 105 Pa.)

Accepted Answer

A)  11.6 × 105 Pa 
B)  11.6 × 104 Pa 
C)  2.94 × 105 Pa 
D)  2.94 × 104 Pa 
E)  2.94 × 103 Pa 
A)  11.6 × 105 Pa 
B)  11.6 × 104 Pa 
C)  2.94 × 105 Pa 
D)  2.94 × 104 Pa 
E)  2.94 × 103 Pa

Question 18

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 oil with a density of 820 kg/m3. What is the difference in elevation h if the manometer reading m is 25.0 cm?

Accepted Answer

A)  0.045 m 
B)  0.025 m 
C)  0.065 m 
D)  0.115 m 
E)  0.205 m 
A)  0.045 m 
B)  0.025 m 
C)  0.065 m 
D)  0.115 m 
E)  0.205 m

Question 19

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 20

A barge is 15.0 m wide and 75.0 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 of density 1000 kg/m3?

Accepted Answer

A)  22.6 MN 
B)  13.2 MN 
C)  1.35 MN 
D)  1.13 MN 
E)  11.3 MN 
A)  22.6 MN 
B)  13.2 MN 
C)  1.35 MN 
D)  1.13 MN 
E)  11.3 MN

Exam 18: Fluids

You are driving a late model convertible car at the 65 mph speed limit with its soft flexible roof closed up and the windows closed.You observe that the roof

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.

A flat horizontal plate of area 400 cm2 is dragged over a 0.20 cm thick layer of oil at a speed of 30.0 cm/s.The oil is resting on a fixed horizontal surface. It takes a force 1.20 N applied to the plate to sustain this speed. What is the viscosity of the oil?

A certain coin has a diameter of 21.21 mm,a thickness of 1.95 mm,and weighs 0.04905 N.What is its density?

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?

Incompressible water flows out of a large reservoir through a pipe that opens to the atmosphere 5.70 m below the level of the water in the reservoir. What is the speed of the water as it comes out of the pipe?

A cup of water containing an ice cube at 0°C is filled to the brim.The tip of the ice cube sticks out of the surface.As the ice melts,you observe that

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?

When you blow some air above the upper face of a paper strip,the paper rises.This occurs because

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?

A wooden raft has a mass of 50 kg.When empty it floats in water (density 1000 kg/m3)with 69% of its volume submerged.What mass of sand can be put on the raft without it sinking?

The weight of a car of mass 1.20 × 103 kg is supported equally by the four tires,which are inflated to the same gauge pressure.What gauge pressure in the tires is required so the area of contact of each tire with the road is 1.00 × 102 cm2? (1 atm = 1.01 × 105 Pa.)

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 oil with a density of 820 kg/m3. What is the difference in elevation h if the manometer reading m is 25.0 cm?

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

A barge is 15.0 m wide and 75.0 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 of density 1000 kg/m3?

Foundations

A: Foundations

Motion in One Dimension

Acceleration

Momentum

Energy

Principle of Relativity

Interactions

Force

Work

Motion in a Plane

Motion in a Circle

Torque

Gravity

Special Relativity

Periodic Motion

Waves in One Dimension

Waves in Two and Three Dimensions

Entropy

Energy Transferred Thermally

Degradation of Energy

Electric Interactions

The Electric Field

Gausss Law

Work and Energy in Electrostatics

Charge Separation and Storage

Magnetic Interactions

Magnetic Fields of Charged Particles in Motion

Changing Magnetic Fields

Changing Electric Fields

Electric Circuits

Electronics

Ray Optics

Wave and Particle Optics

Filters

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.

A flat horizontal plate of area 400 cm² is dragged over a 0.20 cm thick layer of oil at a speed of 30.0 cm/s.The oil is resting on a fixed horizontal surface. It takes a force 1.20 N applied to the plate to sustain this speed. What is the viscosity of the oil?

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?

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?

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?

A wooden raft has a mass of 50 kg.When empty it floats in water (density 1000 kg/m³)with 69% of its volume submerged.What mass of sand can be put on the raft without it sinking?

The weight of a car of mass 1.20 × 10³ kg is supported equally by the four tires,which are inflated to the same gauge pressure.What gauge pressure in the tires is required so the area of contact of each tire with the road is 1.00 × 10² cm²? (1 atm = 1.01 × 10⁵ Pa.)

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 oil with a density of 820 kg/m³. What is the difference in elevation h if the manometer reading m is 25.0 cm?

A barge is 15.0 m wide and 75.0 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 of density 1000 kg/m³?