Deck 10: Fluids

Question 1

A reading of a tire gauge tells you that the gauge pressure in a tire is 30 . What is the absolute pressure in the tire? Assume that atmospheric pressure is 14 .

A) 30 .
B) 16 .
C) 44 .
D) You can't be sure since you may have nitrogen-filled tires.

Answer 1

44 .

Question 2

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. Dam #2 is twice as high and three 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) 24
B) 12
C) 6
D) 3

Answer 2

12

Question 3

A stonecutter's chisel has an edge area of 0.40 cm². If the chisel is struck with a force of 45 N, what is the pressure exerted on the stone?

A) 1.1 *10⁶ Pa
B) 1.1 * 10⁵ Pa
C) 5.5 * 10⁴ Pa
D) 1.1 *10³ Pa

Answer 3

1.1 *10⁶ Pa

Question 4

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) M²L ^{- 1}T ^{- 3}.
D) a dimensionless quantity.

Question 5

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/cm³

Question 6

A solid object is made of two materials, one material having density of 2000 kg/m³ and the other having density of 8000 kg/m³. If the object contains equal volumes of the materials, what is its average density?

A) 3000 kg/m³
B) 3200 kg/m³
C) 5000 kg/m³
D) more information is needed

Question 7

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 0.40 atm?

A) 120,000 N
B) 12,000 N
C) 1200 N
D) 120 N

Question 8

A solid object is made of two materials, one material having density of 2000 kg/m³ and the other having density of 6000 kg/m³. If the object contains equal masses of the materials, what is its average density?

A) 3000 kg/m³
B) 3200 kg/m³
C) 5000 kg/m³
D) more information is needed

Question 9

The water behind Grand Coulee Dam is 1200 m wide and 160 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) 15.1 * 10¹⁰ N

Question 10

What is the total force on the bottom of a filled 4.0-m diameter by 1.0-m deep round wading pool due to the weight of the air and the weight of the water? (Note that the pressure contribution from the atmosphere is 1.0 *10⁵ N/m², the density of water is 1000 kg/m³, and g = 9.8 m/s².)

A) 3.4 * 10⁵ N
B) 1.4 *10⁶ N
C) 1.7 * 10⁵ N
D) 7.8 * 10⁵ N

Question 11

The Greenland ice sheet can be one km thick. Estimate the pressure underneath the ice where it is 0.80 km deep. (The density of ice is 918 kg/m³.)

A) 9.0 * 10⁵ Pa (9 atm)
B) 2.5* 10⁶ Pa (25 atm)
C) 7.2 *10⁶ Pa (72 atm)
D) 9.0 *10⁶ Pa (90 atm)

Question 12

If the column of mercury in a barometer stands at 69.4 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

Question 13

By what factor is the total pressure greater at a depth of 650 m in water than at the surface where the 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) 64
D) 19

Question 14

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.

Question 15

A container is filled with water, and the pressure at the bottom of the container is P. Then the container is emptied halfway and topped off with oil of density 0.80 * 10³ kg/m³, which floats on top of the water. What is the pressure at the bottom of the container now?

A) a pressure < P
B) the same pressure P
C) a pressure > P
D) This is unable to be determined with the information given.

Question 16

A container is filled with water and the pressure at the container bottom is P. If the container is instead filled with oil having a density of 0.80 that of water, what new bottom pressure results?

A) a pressure < P
B) the same pressure P
C) a pressure > P
D) This is unable to be determined with the information given.

Question 17

At a pressure of 1 atmosphere a column of mercury in a barometer is supported to the height h = 0.76 m. The density of mercury is 13.6 *10³ kg/m³. A barometer of similar design filled with water would support a column of water how high at a pressure of 1 atmosphere?

A) more than ten times h
B) about 1.36h
C) less than one tenth h
D) the same height h

Question 18

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) 7900 m
B) 77,000 m
C) 1260 m
D) 10,300 m

Question 19

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

Question 20

How deep under the surface of a lake would the pressure be triple that at the surface? (1 atm = 1.01 *10⁵ Pa)

A) 1.00 m
B) 9.80 m
C) 10.3 m
D) 20.6 m

Question 21

A U-tube is partially filled with water and then an immiscible liquid is added to the right side. The top of the liquid is a distance above the level of interface between the liquid and water. On the left side of the tube the top of the water is a distance above the liquid-water interface on the right side. What is the density of the liquid in terms of the density of water ? Note that .

A)
B)
C)
D)

Question 22

A balloon of negligible mass is filled with 300 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) 150 kg
B) 300 kg
C) 333 kg
D) 444 kg

Question 23

A block of wood has density 0.50 g/cm³ and mass 2250 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) 3000 cm³
B) 2250 cm³
C) 1500 cm³
D) 1000 cm³

Question 24

A ping-pong ball has an average density of 0.140 g/cm³ and a diameter of 3.80 cm. What force would be required to keep the ball completely submerged under water?

A) 0.484 N
B) 0.242 N
C) 0.516 N
D) 0.258 N

Question 25

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.

Question 26

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.

Question 27

A piece of aluminum has density 2.70 g/cm³ and mass 834 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) 633 g
C) 588 g
D) 190 g

Question 28

A syringe has an inside radius of its barrel of 0.50 cm and at the opening at the end of the needle the radius is 1.0 mm. If a force F is applied to the plunger, what is the force produced at the opening of the needle?

A) 5F
B) 25F
C) F/5
D) F/25

Question 29

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.

Question 30

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 440 g, what volume would be necessary to prove that it is pure gold?

A) 31.1 cm³
B) 114* 10³ cm³
C) 22.8 cm³
D) 1.81 *10^-2 cm³

Question 31

A block of wood has a density of 650 kg/m³. When placed in water, what percent of the volume of the wood is above the surface?

A) 0, the block sinks.
B) 30%
C) 35%
D) 65%

Question 32

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 6.43 kg. What is the density of the rock? (water density = 1000 kg/m³)

A) 1.40 *10³ kg/m³
B) 3.50 * 10³ kg/m³
C) 1.84 * 10³ kg/m³
D) 1.58 *10³ kg/m³

Question 33

An ice cube with a small solid steel sphere frozen inside floats in a glass of water filled to the brim. What happens to the level of water in the glass as a result of the ice melting?

A) It goes up, overflowing.
B) It stays the same.
C) It goes down.
D) It depends on air pressure, thus the answer is indeterminate.

Question 34

What volume of water is displaced by a submerged 16-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) 1.5 *10^-3 m³
C) 9.9 *10³ m³
D) 5.9 *10^-3 m³

Question 35

A piece of aluminum has density 2.70 g/cm³ and mass 834 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) 1125 cm³

Question 36

A cube of wood of density 0.64 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) 3.6 cm
C) 2.2 cm
D) 6.4 cm

Question 37

The bottom of a flat-bottomed aluminum boat has area = 4.0 m² and mass = 120 kg. If two fishermen and their fishing gear with total mass of 240 kg are placed in the boat, how much lower will the boat ride in the water? (water density = 1.0 * 10³ kg/m³)

A) 0.15 m
B) 0.090 m
C) 0.075 m
D) 0.060 m

Question 38

The bottom of a flat-bottomed aluminum boat has an area of 4.0 m², and the boat's mass is 120 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

Question 39

At the altitude h the atmospheric pressure is half the pressure at sea level. Let equal the atmospheric pressure at sea level. What is the atmospheric pressure at an altitude 2h?

A) 0, since this is at twice the altitude where the pressure halves.
B) 0.37
C) 0.25
D) The answer is not given.

Question 40

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 0.050-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) 940 N
C) 3000 N
D) 15,000 N

Question 41

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 4.0 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) 150 Pa

Question 42

An ideal fluid flows through a pipe made of two sections with diameters of 1.0 and 2.0 inches, respectively. The speed of the fluid flow through the 2.0-inch section will be what factor times that through the 1.0-inch section?

A) 1/4
B) 1/2
C) 8
D) 4

Question 43

Water (density = 1 *10³ kg/m³) flows at 16 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

Question 44

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 4.3 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

Question 45

Water (density = 1*10³ kg/m³) flows at 10 m/s through a pipe with radius 0.040 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) 0.045 m
B) 0.034 m
C) 0.015 m
D) 0.012 m

Question 46

How much air must be pushed downward at 60.0 m/s to keep an 800-kg helicopter aloft?

A) 131 kg/s
B) 196 kg/s
C) 294 kg/s
D) 392 kg/s

Question 47

A fountain sends water to a height of 50 m. What must be the pressurization (above atmospheric) of the underground water system? (1 atm = 10⁵ N/m²)

A) 1 atm
B) 4.9 atm
C) 7.2 atm
D) 9.8 atm

Question 48

An ideal fluid, of density 0.90 *10³ kg/m³, flows at 12 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 a radius of 1.5 cm. Find the speed of flow in the second pipe.

A) 54 m/s
B) 1.3 m/s
C) 0.67 m/s
D) 0.33 m/s

Question 49

A block of wood is floating in water. If the temperature of the water increases, what happens to the fraction of the block above water?

A) It increases.
B) It decreases.
C) It stays the same.
D) It can be any of the above answers depending on the initial and final temperatures.

Question 50

Water pressurized to 4 * 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

Question 51

The flow rate of blood through the average human aorta, of radius 0.95 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

Question 52

A Boeing-737 airliner has a mass of 30,000 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) 1960 Pa
B) 2940 Pa
C) 7840 Pa
D) 15,700 Pa

Question 53

When an artery gets a constricted region due to plaque, how does the pressure in this region compare to the pressure in an unconstricted region adjacent?

A) Since this is a closed system, the pressure is the same in both regions.
B) In the constricted region the blood moves at a higher speed than in the unconstricted region, resulting in an increased pressure.
C) In the constricted region the blood moves at a higher speed than in the unconstricted region, resulting in a decreased pressure.
D) In the constricted region the blood moves at a lower speed than in the unconstricted region, resulting in an increased pressure.

Question 54

A hole is poked through the metal side of a drum holding water. The hole is 28 cm below the water surface. What is the initial speed of outflow?

A) 1.9 m/s
B) 2.3 m/s
C) 3.2 m/s
D) 3.5 m/s

Question 55

Water comes down the spillway of a dam from an initial vertical height of 100 m. What is the highest possible speed of the water at the end of the spillway?

A) 15 m/s
B) 44 m/s
C) 58 m/s
D) 1370 m/s

Question 56

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.

Question 57

The flow rate of a liquid through a 2.0-cm radius pipe is 0.016 m³/s. The average fluid speed in the pipe is:

A) 0.64 m/s.
B) 13 m/s.
C) 0.040 m/s.
D) 6.4 m/s.

Question 58

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 2.0 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

Question 59

An ideal fluid, of density 0.85 * 10³ kg/m³, flows at 0.50 kg/s through a pipe of radius 0.010 m. What is the fluid speed?

A) 0.95 m/s
B) 1.9 m/s
C) 3.0 m/s
D) 0.94 m/s

Question 60

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 0.080 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) 25 m/s
D) 0.99 m/s

Question 61

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 15 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) 4.4 *10^-5 m/s
D) 8.8 *10^-5 m/s

Question 62

Spherical particles of density 3.0 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) 2.6 *10^-6 m
D) 5.6 *10^-6 m

Question 63

How much power is theoretically available from a mass flow of 1000 kg/s of water that falls a vertical distance of 50 m?

A) 980 kW
B) 98 kW
C) 4900 W
D) 490 kW

Question 64

A pipe of diameter 4 cm is replaced by one of the same length but of diameter 5 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) 5.1
B) 3.4
C) 2.4
D) 1.5

Question 65

Water is sent from a fire hose at 40 m/s at an angle of 30 $\degree$ above the horizontal. What is the maximum height reached by the water?

A) 7.5 m
B) 11 m
C) 15 m
D) 20 m

Question 66

A fluid has a density of 1040 kg/m³. If it rises to a height of 1.8 cm in a 2.0-mm diameter capillary tube, what is the surface tension of the liquid?

A) 0.046 N/m
B) 0.056 N/m
C) 0.092 N/m
D) 0.11 N/m

Question 67

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 15 m/s, what is the speed of the water inside the hose?

A) 0.63 m/s
B) 0.94 m/s
C) 2.5 m/s
D) also 10 m/s

Question 68

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.

Question 69

It takes 2.0 minutes to fill a gas tank with 60 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? (1000 liters = one cubic meter)

A) 0.27 m/s
B) 1.1 m/s
C) 1.6 m/s
D) 64 m/s

Question 70

A centrifuge rotates at 100 rev/s (i.e., 628 rad/s). If the test tube places the suspension at 10 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 * 10³
B) 64
C) 800
D) 4.0 * 10⁴

Question 71

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.

Question 72

The fluid to which Bernoulli's equation is applied is based on what being conserved for the fluid?

A) its momentum
B) its potential energy
C) its kinetic energy
D) its total mechanical energy

Question 73

The equation of continuity applied to an incompressible ideal fluid flowing through a pipe of varying diameter is based on what of the following being conserved for the fluid in the pipe?

A) its kinetic energy
B) its momentum
C) its flow rate
D) its potential energy

Question 74

The SI units for viscosity are N·s/m². Another commonly used unit for viscosity is the poise, where 10 poise = 1 N·s/m². The poise is a fairly large unit, and it is more common to use the centipoise. Which of the following is equal to the centipoise?

A) 10^-3 N·s/m²
B) 10^-2 N·s/m²
C) 10^-1 N·s/m²
D) 10² N·s/m²