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

A 12,000-N car is raised using a hydraulic lift, which consists of a U-tube with arms of unequal areas, filled with incompressible 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, you can 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 C

Question 3

An incompressible fluid flows steadily through a pipe that has a change in diameter. The fluid speed at a location where the pipe diameter is 8.0 cm is 1.28 m/s. What is the fluid speed at a location where the diameter has narrowed to 4.0 cm?

Accepted Answer

A)  0.32 m/s 
B)  0.64 m/s 
C)  1.28 m/s 
D)  2.56 m/s 
E)  5.12 m/s 
A)  0.32 m/s 
B)  0.64 m/s 
C)  1.28 m/s 
D)  2.56 m/s 
E)  5.12 m/s E

Question 4

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 5

If you double the pressure on the surface of a can of water, the buoyant force on a stone placed in that water will

Accepted Answer

A)  increase, but not double. 
B)  double. 
C)  decrease, but not by one-half. 
D)  not change. 
A)  increase, but not double. 
B)  double. 
C)  decrease, but not by one-half. 
D)  not change.

Question 6

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 7

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 8

A steel rod 55 cm long has a diameter of 30 cm. The compressive strength (the maximum stress it can support without breaking) of this steel is 500 × 106 N/m2. What is the compression force that would break the rod?

Accepted Answer

A)  3.5 × 107 N 
B)  2.4 × 107 N 
C)  1.4 × 108 N 
D)  4.7 × 108 N 
E)  8.9 × 108 N 
A)  3.5 × 107 N 
B)  2.4 × 107 N 
C)  1.4 × 108 N 
D)  4.7 × 108 N 
E)  8.9 × 108 N

Question 9

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 net force does the water exert on the lower face of the cylinder?

Accepted Answer

A)  7.40 × 103 N 
B)  1.09 × 104 N 
C)  3.79 × 104 N 
D)  4.14 × 104 N 
E)  1.37 × 105 N 
A)  7.40 × 103 N 
B)  1.09 × 104 N 
C)  3.79 × 104 N 
D)  4.14 × 104 N 
E)  1.37 × 105 N

Question 10

Tensile stress is

Accepted Answer

A)  the strain per unit length. 
B)  the same as force. 
C)  the ratio of the change in length to the original length. 
D)  the applied force per cross-sectional area. 
E)  the ratio of elastic modulus to strain. 
A)  the strain per unit length. 
B)  the same as force. 
C)  the ratio of the change in length to the original length. 
D)  the applied force per cross-sectional area. 
E)  the ratio of elastic modulus to strain.

Question 11

Consider a very small hole in the bottom of a tank 20.0 cm in diameter filled with water to a height of 50.0 cm. 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 
A)  3.13 m/s 
B)  9.80 m/s 
C)  31.8 m/s 
D)  34.9 m/s

Question 12

Two compressible solids are formed into spheres of the same size. The bulk modulus of sphere two is twice as large as the bulk modulus of sphere one. You now increase the pressure on both spheres by the same amount. As a result of the increased pressure, how is the change in volume of sphere two (△V2) related to the change in volume of sphere one (ΔV1)?

Accepted Answer

A)  ΔV2 = 2ΔV1 
B)  ΔV2 = 4ΔV1 
C)  vV2 = ΔV1 
D)  ΔV2 = 1/2ΔV1 
E)  ΔV2 = 1/4ΔV1 
A)  ΔV2 = 2ΔV1 
B)  ΔV2 = 4ΔV1 
C)  vV2 = ΔV1 
D)  ΔV2 = 1/2ΔV1 
E)  ΔV2 = 1/4ΔV1

Question 13

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 14

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.

Question 15

A sample of tendon 3.00 cm long and 4.00 mm in diameter is found to break under a minimum force of 128 N. If instead the sample had been 1.50 cm long and of uniform composition and cross-sectional area, what minimum force would have been required to break it?

Accepted Answer

A)  32 N 
B)  64 N 
C)  128 N 
D)  256 N 
E)  512 N 
A)  32 N 
B)  64 N 
C)  128 N 
D)  256 N 
E)  512 N

Question 16

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 17

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

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

A steel guitar string with a diameter of 0.300 mm and a length of 70.0 cm is stretched by 0.500 mm while being tuned. How much force is needed to stretch the string by this amount? Young's modulus for steel is 2.0 × 1011 N/m2.

Accepted Answer

Question 20

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

Exam 15: Fluids and Elasticity

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

An incompressible fluid flows steadily through a pipe that has a change in diameter. The fluid speed at a location where the pipe diameter is 8.0 cm is 1.28 m/s. What is the fluid speed at a location where the diameter has narrowed to 4.0 cm?

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

If you double the pressure on the surface of a can of water, the buoyant force on a stone placed in that water will

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?

A steel rod 55 cm long has a diameter of 30 cm. The compressive strength (the maximum stress it can support without breaking) of this steel is 500 × 106 N/m2. What is the compression force that would break the rod?

Tensile stress is

Consider a very small hole in the bottom of a tank 20.0 cm in diameter filled with water to a height of 50.0 cm. Find the speed at which the water exits the tank through the hole.

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?

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 sample of tendon 3.00 cm long and 4.00 mm in diameter is found to break under a minimum force of 128 N. If instead the sample had been 1.50 cm long and of uniform composition and cross-sectional area, what minimum force would have been required to break it?

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?

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 steel guitar string with a diameter of 0.300 mm and a length of 70.0 cm is stretched by 0.500 mm while being tuned. How much force is needed to stretch the string by this amount? Young's modulus for steel is 2.0 × 1011 N/m2.

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.)

Concepts of Motion

Kinematics in One Dimension

Vectors and Coordinate Systems

Kinematics in Two Dimensions

Force and Motion

Dynamics I: Motion Along a Line

Newtons Third Law

Dynamics Ii: Motion in a Plane

Impulse and Momentum

Energy

Work

Rotation of a Rigid Body

Newtons Theory of Gravity

Oscillations

A Macroscopic Description of Matter

Work, Heat, and the First Law of Thermodynamics

The Micromacro Connection

Heat Engines and Refrigerators

Traveling Waves

Superpositions

Wave Optics

Ray Optics

Optical Instruments

Electric Charges and Forces

The Electric Field

Gausss Law

The Electric Potential

Potential and Field

Current and Resistance

Fundamentals of Circuits

The Magnetic Field

Electromagnetic Induction

Electromagnetic Fields and Waves

Ac Circuits

Relativity

The Foundations of Modern Physics

Quantization

Wave Functions and Uncertainty

One-Dimensional Quantum Mechanics

Atomic Physics

Nuclear Physics

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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?

A steel rod 55 cm long has a diameter of 30 cm. The compressive strength (the maximum stress it can support without breaking) of this steel is 500 × 10⁶ N/m². What is the compression force that would break the rod?

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?

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?

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 steel guitar string with a diameter of 0.300 mm and a length of 70.0 cm is stretched by 0.500 mm while being tuned. How much force is needed to stretch the string by this amount? Young's modulus for steel is 2.0 × 10¹¹ N/m².

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.)