Physics Chapter 9

12. The standard kilogram is a platinum-iridium cylinder 39.0 mm in height and 39.0 mm in diameter. What is the density of the material? a. 21.5 g/cm3 b. 19.3 g/cm3 c. 13.6 g/cm3 d. 10.7 g/cm

A

20. A solid object is made of two materials, one material having density of 2 000 kg/m3 and the other having density of 6 000 kg/m3 . If the object contains equal masses of the materials, what is its average density? a. 3 000 kg/m3 b. 4 000 kg/m3 c. 5 300 kg/m3 d. more information is needed

A

21. What is the total force on the bottom of a 2.0-m-diameter by 1.0-m-deep round wading pool due to the weight of the air and the weight of the water? (Note the pressure contribution from the atmosphere is 1.0 × 105 N/m2 , the density of water is 1 000 kg/m3 , and g = 9.8 m/s2 .) a. 3.4 × 105 N b. 2.4 × 106 N c. 3.2 × 106 N d. 6.0 × 106 N

A

25. If the column of mercury in a barometer stands at 72.6 cm, what is the atmospheric pressure? (The density of mercury is 13.6 × 103 kg/m3 and g = 9.80 m/s2 ) a. 0.968 × 105 N/m2 b. 1.03 × 105 N/m2 c. 0.925 × 105 N/m2 d. 1.07 × 105 N/m2

A

27. Atmospheric pressure is 1.0 × 105 N/m2 , and the density of air is 1.29 kg/m3 . If the density of air is constant as you get higher and higher, calculate the height of the atmosphere needed to produce this pressure. a. 7 900 m b. 77 000 m c. 1 260 m d. 10 300 m

A

30. A piece of aluminum has density 2.70 g/cm3 and mass 775 g. The aluminum is submerged in a container of oil (oil's density = 0.650 g/cm3 ). How much oil does the metal displace? a. 287 cm3 b. 309 cm3 c. 232 cm3 d. 1 125 cm

A

33. What volume of water is displaced by a submerged 2.0-kg cylinder made of solid aluminum? (aluminum density = 2.7 × 103 kg/m3 and water density = 1.0 × 103 kg/m3 ) a. 7.4 × l0−4 m3 b. 1.4 × 103 m3 c. 9.9 × 103 m3 d. 6.0 × 102 m

A

38. Legend says that Archimedes, in determining whether or not the king's crown was made of pure gold, measured its volume by the water displacement method. If the density of gold is 19.3 g/cm3 , and the crown's mass is 600 g, what volume would be necessary to prove that it is pure gold? a. 31.1 cm3 b. 114 × 103 cm3 c. 22.8 × 103 cm3 d. 1.81 × 10−2 cm3

A

44. A heavily loaded boat is floating in a pond. The boat starts to sink because of a leak but quick action plugging the leak stops the boat from going under although it is now deeper in the water. What happens to the surface level of the pond? a. It stays the same. b. It goes up. c. It goes down. d. More information is needed to reach a conclusion.

A

52. Water (density = 1 × 103 kg/m3 ) flows at 15 m/s through a pipe with radius 0.040 m. The pipe goes up to the second floor of the building, 3.0 m higher, and the pressure remains unchanged. What is the speed of the water flow in the pipe on the second floor? a. 13 m/s b. 14 m/s c. 15 m/s d. 16 m/s

A

55. A hole is poked through the metal side of a drum holding water. The hole is 18 cm below the water surface. What is the initial speed of outflow? a. 1.9 m/s b. 2.96 m/s c. 3.2 m/s d. 3.5 m/s

A

57. Water pressurized to 3 × 105 Pa is flowing at 5.0 m/s in a pipe which contracts to 1/3 of its former area. What are the pressure and speed of the water after the contraction? (Density of water = 1 × 103 kg/m3 .) a. 2 × 105 Pa, 15 m/s b. 3 × 105 Pa, 10 m/s c. 3 × 105 Pa, 15 m/s d. 4 × 105 Pa, 1.5 m/s

A

60. A Boeing-737 airliner has a mass of 20 000 kg. The total area of the wings is 100 m2 . What must be the pressure difference between the top and bottom of the wings to keep the airplane up? a. 1 960 Pa b. 3 920 Pa c. 7 840 Pa d. 15 700 Pa

A

62. A jet of water flowing from a hose at 15 m/s is directed against a wall. If the mass flow in the fluid stream is 2.0 kg/s, what force is the water applying to the wall if backsplash is negligible? a. 30 N b. 40 N c. 65 N d. 127 N

A

65. How much power is theoretically available from a mass flow of 1 000 kg/s of water that falls a vertical distance of 100 m? a. 980 kW b. 98 kW c. 4 900 W d. 980 W

A

68. Water is being sprayed from a nozzle at the end of a garden hose of diameter 2.0 cm. If the nozzle has an opening of diameter 0.50 cm, and if the water leaves the nozzle at a speed of 10 m/s, what is the speed of the water inside the hose? a. 0.63 m/s b. 0.80 m/s c. 2.5 m/s d. also 10 m/s

A

69. A unit for viscosity, the centipoise, is equal to which of the following? a. 10-3 N·s/m2 b. 10-2 N·s/m2 c. 10-1 N·s/m2 d. 102 N·s/m2

A

71. A fluid has a density of 1 040 kg/m3 . If it rises to a height of 1.8 cm in a 1.0-mm diameter capillary tube, what is the surface tension of the liquid? Assume a contact angle of zero. a. 0.046 N/m b. 0.056 N/m c. 0.092 N/m d. 0.11 N/m

A

72. A pipe carrying water has a radius of 1.0 cm. If the flow velocity is 9.0 cm/s, which of the following characterizes the flow? Take the viscosity of water to be 1.0 × 10-3 N·s/m. a. streamlined b. unstable c. turbulent d. stagnant

A

73. In order to overcome a surface tension of a fluid, a force of 1.32 × 10-2 N is required to lift a wire ring of circumference 12.0 cm. What is the surface tension of the fluid? a. 0.055 N/m b. 0.11 N/m c. 0.035 N/m d. 0.018 N/m

A

76. Spherical particles of density 2.0 g/cm3 are shaken in a container of water (viscosity = 1.0 × 10-3 N·s/m3 ). The water is 8.0 cm deep and is allowed to stand for 30 minutes. What is the radius of the largest particles still in suspension at that time? a. 4.5 × 10-6 m b. 9.0 × 10-6 m c. 2.3 × 10-6 m d. 5.6 × 10-6 m

A

77. A centrifuge rotates at 100 rev/s (i.e., 628 rad/s). If the test tube places the suspension at 8.0 cm from the axis of rotation, by what factor are the terminal speeds of the settling particles increased as compared to sedimentation cause by gravity? a. 3.2 × 102 b. 64 c. 800 d. 3.9 × 105

A

A 15 000-N car on a hydraulic lift rests on a cylinder with a piston of radius 0.20 m. If a connecting cylinder with a piston of 0.040-m radius is driven by compressed air, what force must be applied to this smaller piston in order to lift the car? a. 600 N b. 1 500 N c. 3 000 N d. 15 000 N

A

1. Which state of matter is associated with the very highest of temperatures? a. liquid b. plasma c. gas d. solid

B

11. How large a force is necessary to stretch a 2.0-mm-diameter steel wire (Y = 2.0 × 1011 N/m2 ) by 1.0%? a. 3.1 × 103 N b. 6.3 × 103 N c. 9.4 × 103 N d. 1.3 × 104 N

B

13. The quantity "pressure" expressed in terms of the fundamental quantities (mass, length, time) is equivalent to: a. MLT−1 . b. ML−1 T−2 . c. M2 L−1 T−3 . d. a dimensionless quantity.

B

24. By what factor is the total pressure greater at a depth of 850 m in water than at the surface where pressure is one atmosphere? (water density = 1.0 × 103 kg/m3 , 1 atmosphere pressure = 1.01 × 105 N/m2 , and g = 9.8 m/s2 ) a. 100 b. 83 c. 74 d. 19

B

32. A block of wood has density 0.50 g/cm3 and mass 1 500 g. It floats in a container of oil (the oil's density is 0.75 g/cm3 ). What volume of oil does the wood displace? a. 3 000 cm3 b. 2 000 cm3 c. 1 500 cm3 d. 1 000 cm

B

36. The bottom of a flat-bottomed aluminum boat has an area of 4.0 m2 and the boat's mass is 60 kg. When set afloat in water, how far below the water surface is the boat bottom? (water density = 1.0 × 103 kg/m3 ) a. 0.060 m b. 0.015 m c. 0.030 m d. 0.075 m

B

4. The quantity "stress" expressed in terms of the fundamental quantities (mass, length, time) is equivalent to: a. MLT−1 . b. ML−1 T−2 . c. M2 L−1 T−3 . d. a dimensionless quantity.

B

45. A block of wood has specific gravity 0.80. When placed in water, what percent of the volume of the wood is above the surface? a. 0, the block sinks. b. 20% c. 25% d. 80%

B

53. Water (density = 1 × 103 kg/m3 ) flows at 10 m/s through a pipe with radius 0.030 m. The pipe goes up to the second floor of the building, 2.0 m higher, and the pressure remains unchanged. What is the radius of the pipe on the second floor? a. 0.046 m b. 0.034 m c. 0.015 m d. 0.012 m

B

54. Air pressure is 1.0 × 105 N/m2 , air density is 1.3 kg/m3 , and the density of soft drinks is 1.0 × 103 kg/m3 . If one blows carefully across the top of a straw sticking up 0.100 m from the liquid in a soft drink can, it is possible to make the soft drink rise half way up the straw and stay there. How fast must the air be blown across the top of the straw? a. 76 m/s b. 27 m/s c. 19 m/s d. 0.99 m/s

B

61. How much air must be pushed downward at 40.0 m/s to keep an 800-kg helicopter aloft? a. 98.0 kg/s b. 196 kg/s c. 294 kg/s d. 392 kg/s

B

63. A Venturi tube may be used as the inlet to an automobile carburetor. If the inlet pipe of 2.0 cm diameter narrows to 1.0 cm diameter, what is the pressure drop in the constricted section for airflow of 3.0 m/s in the 2-cm section? (Assume air density is 1.25 kg/m3 .) a. 70 Pa b. 84 Pa c. 100 Pa d. 115 Pa

B

64. Water is sent from a fire hose at 30 m/s at an angle of 30° above the horizontal. What is the maximum height reached by the water? a. 7.5 m b. 11 m c. 15 m d. 19 m

B

67. It takes 2.0 minutes to fill a gas tank with 40 liters of gasoline. If the pump nozzle is 1.0 cm in radius, what is the average speed of the gasoline as it leaves the nozzle? (1 000 liters = one cubic meter) a. 0.27 m/s b. 1.1 m/s c. 11 m/s d. 64 m/s

B

9. A solid object is made of two materials, one material having density of 2 000 kg/m3 and the other having density of 6 000 kg/m3 . If the object contains equal volumes of the materials, what is its average density? a. 3 000 kg/m3 b. 4 000 kg/m3 c. 5 300 kg/m3 d. more information is needed

B

0. The condition for onset of turbulent flow is that the Reynolds Number reaches what value? a. 1 000 b. 2 000 c. 3 000 d. 4 000

C

10. A tire stops a car by use of friction. What modulus should we use to calculate the stress and strain on the tire? a. Young's modulus b. compression modulus c. shear modulus d. bulk modulus

C

18. What is the total mass of the Earth's atmosphere? (The radius of the Earth is 6.4 × 106 m, and atmospheric pressure at the surface is 105 N/m2 .) a. 5 × 1016 kg b. 1 × 1018 kg c. 5 × 1018 kg d. 1 × 1020 kg

C

26. Dams at two different locations are needed to form a lake. When the lake is filled, the water level will be at the top of both dams. The Dam #2 is twice as high and twice as wide as Dam #1. How much greater is the force of the water on Dam #2 than the force on Dam #1? (Ignore atmospheric pressure; it is pushing on both sides of the dams.) a. 2 b. 4 c. 8 d. 16

C

28. The water behind Grand Coulee Dam is 1 200 m wide and 150 m deep. Find the hydrostatic force on the back of the dam. (Hint: the total force = average pressure × area) a. 5.2 × 109 N b. 8.8 × 1010 N c. 13.2 × 1010 N d. 18.0 × 1010 N

C

29. How deep under the surface of a lake would the pressure be double that at the surface? (1 atm = 1.01 × 105 Pa) a. 1.00 m b. 9.80 m c. 10.3 m d. 32.2 m

C

31. A piece of aluminum has density 2.70 g/cm3 and mass 775 g. The aluminum is submerged in a container of oil of density 0.650 g/cm3 . A spring balance is attached with string to the piece of aluminum. What reading will the balance register in grams (g) for the submerged metal? a. 960 g b. 775 g c. 588 g d. 190 g

C

35. A cube of wood of density 0.78 g/cm3 is 10 cm on a side. When placed in water, what height of the block will float above the surface? (water density = 1.00 g/cm3 ) a. 7.8 cm b. 5.0 cm c. 2.2 cm d. 6.4 cm

C

37. The bottom of a flat-bottomed aluminum boat has area = 4.0 m2 and mass = 60 kg. If two fishermen and their fishing gear with total mass of 300 kg are placed in the boat, how much lower will the boat ride in the water? (H2O density = 1.0 × 103 kg/m3 ) a. 0.15 m b. 0.090 m c. 0.075 m d. 0.060 m

C

40. As ice floats in water, about 10% of the ice floats above the surface of the water. If we float some ice in a glass of water, what will happen to the water level as the ice melts? a. The water level will rise 10% of the volume of the ice that melts. b. The water level will rise, but not as much as the 10% indicated in answer a. c. The water level will remain unchanged. d. The water level will become lower.

C

43. A heavily loaded boat is floating in a pond. The boat sinks because of a leak. What happens to the surface level of the pond? a. It stays the same. b. It goes up. c. It goes down. d. More information is needed to reach a conclusion.

C

50. An ideal fluid, of density 0.90 × 103 kg/m3 , flows at 6.0 m/s through a level pipe with radius of 0.50 cm. The pressure in the fluid is 1.3 × 105 N/m2 . This pipe connects to a second level pipe, with radius of 1.5 cm. Find the speed of flow in the second pipe. a. 54 m/s b. 18 m/s c. 0.67 m/s d. 0.33 m/s

C

56. Water comes down the spillway of a dam from an initial vertical height of 170 m. What is the highest possible speed of the water at the end of the spillway? a. 15 m/s b. 25 m/s c. 58 m/s d. 1 370 m/s

C

59. The Garfield Thomas water tunnel at Pennsylvania State University has a circular cross-section that constricts from a diameter of 3.6 m to the test section, which is 1.2 m in diameter. If the speed of flow is 3.0 m/s in the large-diameter pipe, determine the speed of flow in the test section. a. 9.0 m/s b. 18 m/s c. 27 m/s d. 1.0 m/s

C

66. A fluid is drawn up through a tube as shown below. The atmospheric pressure is the same at both ends. Use Bernoulli's equation to determine the speed of fluid flow out of the tank. If the height difference from the top of the tank to the bottom of the siphon is 1.0 m, then the speed of outflow is: a. 1.1 m/s. b. 2.2 m/s. c. 4.4 m/s. d. 8.8 m/s.

C

8. Think of Bernoulli's equation as it pertains to an ideal fluid flowing through a horizontal pipe. Imagine that you take measurements along the pipe in the direction of fluid flow. What happens to the sum of the pressure and energy per unit volume? a. It increases as the pipe diameter increases. b. It decreases as the pipe diameter increases. c. It remains constant as the pipe diameter increases. d. No choices above are valid.

C

16. When water freezes, it expands about nine percent. What would be the pressure increase inside your automobile engine block if the water in there froze? (The bulk modulus of ice is 2.0 × 109 Pa, and 1 atm = 1.0 × 105 Pa.) a. 18 atm b. 270 atm c. 1 080 atm d. 1 800 atm

D

17. The Greenland ice sheet can be one km thick. Estimate the pressure underneath the ice. (The density of ice is 918 kg/m3 .) a. 9.0 × 105 Pa (9 atm) b. 2.5 × 106 Pa (25 atm) c. 4.5 × 106 Pa (45 atm) d. 9.0 × 106 Pa (90 atm)

D

2. A copper wire of length 2.0 m, cross sectional area 7.1 × 10−6 m2 and Young's modulus 11 × 1010 N/m2 has a 200-kg load hung on it. What is its increase in length? (g = 9.8 m/s2 ) a. 0.50 mm b. 1.0 mm c. 2.5 mm d. 5.0 mm

D

22. In a large tank of liquid, the hydrostatic pressure at a given depth is a function of: a. depth. b. surface area. c. liquid density. d. Choices a and c are both valid.

D

3. In an elastic solid there is a direct proportionality between strain and: a. elastic modulus. b. temperature. c. cross-sectional area. d. stress.

D

34. A ping-pong ball has an average density of 0.0840 g/cm3 and a diameter of 3.80 cm. What force would be required to keep the ball completely submerged under water? a. 1.000 N b. 0.788 N c. 0.516 N d. 0.258 N

D

39. A solid rock, suspended in air by a spring scale, has a measured mass of 9.00 kg. When the rock is submerged in water, the scale reads 3.30 kg. What is the density of the rock? (water density = 1 000 kg/m3 ) a. 4.55 × 103 kg/m3 b. 3.50 × 103 kg/m3 c. 1.20 × 103 kg/m3 d. 1.58 × 103 kg/m3

D

4. The pressure inside a commercial airliner is maintained at 1.00 atm (105 Pa). What is the net outward force exerted on a 1.0 m × 2.0 m cabin door if the outside pressure is 0.30 atm? a. 140 N b. 1 400 N c. 14 000 N d. 140 000 N

D

41. A large stone is resting on the bottom of the swimming pool. The normal force of the bottom of the pool on the stone is equal to the: a. weight of the stone. b. weight of the water displaced. c. sum of the weight of the stone and the weight of the displaced water. d. difference between the weight of the stone and the weight of the displaced water.

D

42. A blimp is filled with 400 m3 of helium. How big a payload can the balloon lift? (The density of air is 1.29 kg/m3 ; the density of helium is 0.18 kg/m3 .) a. 111 kg b. 129 kg c. 215 kg d. 444 kg

D

46. An ideal fluid flows through a pipe made of two sections with diameters of 1.0 and 3.0 inches, respectively. The speed of the fluid flow through the 3.0-inch section will be what factor times that through the 1.0-inch section? a. 6.0 b. 9.0 c. 1/3 d. 1/9

D

47. The flow rate of a liquid through a 2.0-cm-radius pipe is 0.008 0 m3 /s. The average fluid speed in the pipe is: a. 0.64 m/s. b. 2.0 m/s. c. 0.040 m/s. d. 6.4 m/s.

D

49. An ideal fluid, of density 0.85 × 103 kg/m3 , flows at 0.25 kg/s through a pipe of radius 0.010 m. What is the fluid speed? a. 0.85 m/s b. 1.3 m/s c. 3.0 m/s d. 0.94 m/s

D

5. A stonecutter's chisel has an edge area of 0.50 cm2 . If the chisel is struck with a force of 45 N, what is the pressure exerted on the stone? a. 9 000 Pa b. 90 000 Pa c. 450 000 Pa d. 900 000 Pa

D

5. The quantity "strain" expressed in terms of the fundamental quantities (mass, length, time) is equivalent to: a. MLT−1 . b. ML−1 T−2 . c. M2 L−1 T−3 . d. a dimensionless quantity.

D

51. The flow rate of blood through the average human aorta, of radius 1.0 cm, is about 90 cm3 /s. What is the speed of the blood flow through the aorta? a. 14 cm/s b. 32 cm/s c. 37 cm/s d. 29 cm/s

D

58. A fountain sends water to a height of 100 m. What must be the pressurization (above atmospheric) of the underground water system? (1 atm = 105 N/m2 ) a. 1 atm b. 4.2 atm c. 7.2 atm d. 9.8 atm

D

74. A pipe of diameter three cm is replaced by one of the same length but of diameter six cm. If the pressure difference between the ends of the pipe remains the same, by what factor is the rate of flow of a viscous liquid through it changed? a. 2 b. 4 c. 8 d. 16

D

75. Spherical particles of density 2.0 g/cm3 are shaken in a container of water (viscosity = 1.0 × 10-3 N·s/m3 ). The water is 8.0 cm deep and is allowed to stand for 30 minutes. What is the greatest terminal velocity of the particles still in suspension at that time? a. 0.55 × 10-5 m/s b 1.1 × 10-5 m/s c. 2.2 × 10-5 m/s d. 4.4 × 10-5 m/s

D

78. Which of the following characterizes the net force on a particle falling through a fluid at its terminal speed? a. It is at a maximum. b. It is upwards. c. It is downwards. d. It is zero.

D

8. Bar One has a Young's modulus that is bigger than that of Bar Two. This indicates Bar One: a. is longer than Bar Two. b. has a greater cross-sectional area than Bar Two. c. has a greater elastic limit than Bar Two. d. is made of material that is different from Bar Two.

D

9. Consider two steel rods, A and B. B has three times the area and twice the length of A, so Young's modulus for B will be what factor times Young's modulus for A? a. 3.0 b. 0.5 c. 1.5 d. 1.0

D

A uniform pressure of 7.0 × 105 N/m2 is applied to all six sides of a copper cube. What is the percentage change in volume of the cube? (for copper, B = 14 × 1010 N/m2 ) a. 2.4 × 10−2 % b. 0.4 × 10−2 % c. 8.4 × 10−2 % d. 0.5 × 10−3 %

D

The bulk modulus of a material, as a meaningful physical property, is applicable to which of the following? a. only solids b. only liquids c. only gases d. solids, liquids and gases

D