Deck 11: Fluids

Question 1

Which of the following are the SI units for specific gravity?

A) kg/m³
B) N
C) lb/ft³
D) m/s²
E) specific gravity has no units

Answer 1

specific gravity has no units

Question 2

The left-hand side of an open U-tube has a radius r₁ = 0.82 cm, and the right-hand side has a radius r₂ = 0.41 cm. Mercury and oil are poured into the U-tube. The density of mercury is 13.6 g/cm³. The heights shown in the diagram are h₁ = 3.50 cm and h₂ = 57.3 cm. The density of the oil is approximately

A) 0.83 g/cm³.
B) 110 g/cm³.
C) 7.9 g/cm³.
D) 6.9 g/cm³.
E) 1.82 g/cm³.

Answer 2

0.83 g/cm³.

Question 3

Which of the following is the mass density of a material?

A) the material's weight per unit volume
B) the material's mass per unit volume
C) the material's specific gravity
D) the material's volume per unit weight
E) the material's volume per unit mass

Answer 3

the material's mass per unit volume

Question 4

What is the gauge pressure at a depth of 6 cm in a glass filled with 4 cm of mercury and 4 cm of water? Water has a density of 1000 kg/m³, and mercury has specific gravity of 13.6.

A) 3.1 kPa
B) 5.6 kPa
C) 5.8 kPa
D) 310 kPa
E) 560 kPa

Question 5

An object with specific gravity of 19.3 weighs 0.639 N. What would be the volume of the mass of the object if it was made of material with specific gravity of 13.6?

A) 450 g
B) 45.9 g
C) 0.907 g
D) 92.4 g
E) 651 g

Question 6

A block of material has a density $\rho$ . A second block of equal mass has twice the volume of the first. What is the density of the second block?

A) " $\rho$ "
B) "2 $\rho$ "
C) " $\rho$ /2"
D) "4 $\rho$ "
E) " $\rho$ /4"

Question 7

Two small plates of areas A?₁ and A₂ are immersed in a fluid at the same depth. The pressure and perpendicular force exerted on plates A?₁ and A₂ are p?₁ and p₂ and F?₁ and F₂, respectively. If A₁ > A₂, which of the following statements is true?

A) F₁ > F₂, p₁ > p₂
B) F₁ = F₂, p₁ > p₂
C) F₁ = F₂, p₁ = p₂
D) F₁ > F₂, p₁ = p₂
E) F₁ > F₂, p₁ < p₂

Question 8

A typical donation of whole blood is equal to a pint 473 ml). If the average density of blood $\rho$ _BLOOD = 1060 kg/m³, what is the mass of donated blood?

A) 0.501 kg
B) 0.501 g
C) 0.501 lb
D) 5.01 kg
E) 5.01 g

Question 9

A block of material has a density $\rho$ . A second block of equal volume has three times the mass of the first. What is the density of the second block?

A) " $\rho$ "
B) "3 $\rho$ "
C) " $\rho$ /3"
D) "9 $\rho$ "
E) " $\rho$ /9"

Question 10

Your blood pressure is reported as 50 mm of Hg. The density of mercury is 13.6 g/cm³. Your pressure is equivalent to

A) 6.7 * 10⁶ Pa.
B) 6.8 Pa.
C) 6.8 *10² Pa.
D) 6.7 * 10³ Pa.
E) 3.2 * 10² Pa.

Question 11

Atmospheric pressure at sea level is 101.3 × 10³ Pa. What is the force exerted by the atmosphere on a square foot of area?

A) 101 kN
B) 109 kN
C) 9.41 kN
D) 30.9 kN
E) 332 kN

Question 12

What is a mass of 1.00 mm³ of substance with specific gravity of 2.06?

A) 2.06 g
B) 2.06 mg
C) 2.06 kg
D) 2.06 $\mu$ g
E) 2.06 cg

Question 13

Which gas has the lowest density under standard temperature and pressure?

A) hydrogen
B) helium
C) oxygen
D) nitrogen
E) carbon dioxide

Question 14

An open U-tube has water to a height h on both sides, as shown. The cross-sectional area of the left-hand tube is A₁ = 1.50 cm², and that of the right-hand tube is A₂ = 0.50 cm². A light oil which does not mix with water) with a density of 0.83 g/cm³ is added to the right-hand side. When equilibrium is reached, which of the following is correct?

A) The level on the right-hand side is higher than that on the left.
B) The level on the right-hand side is lower than that on the left.
C) The levels of the two sides are the same.
D) The difference in the heights depends on the ratio of A₁ and A₂.
E) The difference in the height depends on the difference between the areas.

Question 15

The atmospheric pressure deceases exponentially with height. At 5.5 km, the pressure is half that at sea level. At what height is the pressure one eighth that of sea level?

A) 7.5 km
B) 11 km
C) 16.5 km
D) 22 km
E) 27.5 km

Question 16

A container of height, h, is filled with water of density $\rho$ and sealed with a flexible membrane. The container is placed in the space shuttle in orbit. If the air pressure in the shuttle is p_o, the pressure in the middle of the container is

A) "p_o."
B) "p_o + $\rho$ gh."
C) " $\rho$ gh."
D) " $\rho$ gh."
E) "depends how fast the shuttle is moving."

Question 17

If the atmosphere were compressed until it had the density of water, it would cover Earth to a depth of about

A) 0.81 km.
B) 4.6 m.
C) 1.6 km.
D) 76 cm.
E) 10 m.

Question 18

At what depth in seawater is the gauge pressure equal to 1 atm? The density of seawater is 1.03 * 10³ kg/m³.

A) 5 m
B) 7.5 m
C) 10 m
D) 15 m
E) 20 m

Question 19

A penny has a mass of 3.0 g, a diameter of 1.9 cm, and a thickness of 0.15 cm. What is the density of the metal of which it is made?

A) 1.8 g/cm³
B) 3.4 g/cm³
C) 3.5 g/cm³
D) 7.1 g/cm³
E) 4.5 g/cm³

Question 20

A glass is filled with water. The gauge pressure at the top of the glass is zero and the gauge pressure at the bottom is P. A second glass with three times the height and twice the diameter is also filled with water. What is the pressure at the bottom of the second glass?

A) P
B) 2P
C) 3P
D) 3P/2
E) 3P/4

Question 21

A small sphere of wood with a density $\rho$ = 0.40 g/cm³ is held at rest well under the surface of a pool of water. The magnitude of the initial acceleration of the sphere when it is released is

A) 15 m/s².
B) 9.8 m/s².
C) 33 m/s².
D) 23 m/s².
E) 3.4 m/s².

Question 22

A stone of volume 1.42 *10^-2 m³ lies at the bottom of a freshwater lake. If the rock's specific gravity is 3.5, the work required to lift it 1 m through the water is approximately

A) 487 J.
B) 139 J.
C) 348 J.
D) 223 J.
E) 469 J.

Question 23

A tube with a radius of 4.2 cm is holding oil that has a density of 0.92 g/cm³. The gauge pressure in the oil at a depth of 64 cm from the top of the surface is

A) 5.8 *10² Pa.
B) 5.8 * 10³ Pa.
C) 1.0 * 10² Pa.
D) 1.0 *10⁶ Pa.
E) 1.7 * 10³ Pa.

Question 24

The force exerted by a stationary liquid on an inclined rectangular surface at rest in the liquid

A) acts normally to the surface.
B) is exerted equally at all points on the surface.
C) acts parallel to the surface.
D) is independent of the density of the liquid.
E) varies inversely as the depth.

Question 25

If the same fluid fills the containers shown, the pressures at the bases are related according to which of the following expressions?

A) p_C < p_A < p_E < p_D < p_B
B) p_E < p_D < p_C < p_B < p_A
C) p_A < p_B < p_C < p_D < p_E
D) p_E < p_D = p_C < p_B < p_A
E) p_C < p_D < p_E < p_C < p_A

Question 26

The vessels in the figure contain liquids of the same density. The vessel that has the greatest pressure at its base is

A) 1.
B) 2.
C) 3.
D) 4.
E) 5.

Question 27

Two objects made of the same material but of different volumes have the same apparent weight when submerged in water. If they are placed in a vacuum,

A) both weigh less than before.
B) the one with the smaller volume weighs less than the other.
C) the one with the smaller volume weighs more than the other.
D) they weigh the same.
E) both weigh more than before.

Question 28

Which of the following statements is NOT correct?

A) Negative gauge pressure means absolute pressure is below atmospheric.
B) Pressure in a fluid is caused by the impact of molecules.
C) In the same fluid in hydrostatic equilibrium, pressure at the same level is the same.
D) The pressure is proportional to the force the fluid exerts proportional to the object's surface.
E) Force exerted by a fluid on a surface is proportional to pressure and inversely proportional to surface area.

Question 29

A block of ice 30.5 cm thick floating in fresh water just supports a man weighing 801 N. If the specific gravity of ice is 0.917, the smallest area the block can have is

A) 3.22 m².
B) 3.57 m².
C) 2.88 m².
D) 1.45 m².
E) 0.269 m².

Question 30

If a column of liquid 52 cm high supports a column of mercury $\rho$ = 13.6 g/cm³) 10 cm high, the density of the liquid is

A) 6.0 g/cm³.
B) 2.6 g/cm³.
C) 3.8 g/cm³.
D) 4.9 g/cm³.
E) 5.0 g/cm³.

Question 31

A beaker is filled with water. A small plastic container contains a solid bar of aluminum, which has a mass of 40 g, and is placed on the water so that it floats. The water level reads 60 ml. Next, the bar of aluminum is taken out of the container and placed in the water so that it sinks to the bottom. The water level in the beaker _____

A) drops.
B) stays unchanged.
C) rises.
D) depends on the type of container.
E) depends on the ratio of the density of aluminum to the density of the container.

Question 32

According to Pascal's principle, the pressure at every point in a confined liquid

A) depends only on the density of the liquid.
B) is equal to the weight of the liquid.
C) is the same.
D) is changed the same amount by an externally applied pressure.
E) is equal to the externally applied pressure.

Question 33

A piece of wood is floating at the surface of some water as illustrated. The wood has a circular cross section and a height h = 3.0 cm. The density of the wood is 0.41 g/cm³. The distance y from the surface of the water to the bottom of the wood is

A) 1.8 cm.
B) 0.81 cm.
C) 3.2 cm.
D) 1.2 cm.
E) 0.41 cm.

Question 34

A solid wooden sphere of volume 0.0100 m³ floats freely exactly one-half submerged in a liquid of density 800 kg/m³. A lightweight cord is now tied to the sphere and is used to pull the sphere under the surface and hold it completely submerged. What is the tension in the cord?

A)0 N
B) 2.00 N
C) 39.2 N
D) 4.00 N
E) 8.4 N

Question 35

A flat plate with a negligible mass and an area of 1.0 cm² is placed in a horizontal position well beneath the surface in a liquid that is not moving. The pressure at the location of the plate is p Pa. The total force that arises from the pressure of the liquid on this plate is

A) P N, directed down.
B) P × 10^-4 N, directed down.
C) P N, directed up.
D) P × 10^-4 N, directed up.
E) zero.

Question 36

A ball bearing that has a density of 5.16 g/cm³ is held at rest under the surface of a liquid that has a density of 2.50 g/cm³. The magnitude of the acceleration of the ball bearing just after it is released is

A) 5.0 m/s².
B) 14 m/s².
C) 10 m/s².
D) 6.5 m/s².
E) 1.6 m/s².

Question 37

Pressure as a function of depth for a certain liquid is plotted on the graph. What is the density of the liquid?

A) 1.76 g/cm³
B) 1.36 g/cm³
C) 0.340 g/cm³
D) 1.70 g/cm³
E) 3.27 g/cm³

Question 38

A block of wood of relative density 0.750, cross-sectional area of 30.5 cm *40.6 cm, and 20.3 cm thick is tossed into a choppy freshwater lake. After a reasonable time, the approximate vertical dimension above the water will be

A) 2.54 cm.
B) 5.08 cm.
C) 7.62 cm.
D) 10.2 cm.
E) 12.7 cm.

Question 39

Which curve best represents the variation in pressure with depth in a fluid, assuming constant density?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 40

Two pistons of a hydraulic lift have radii of 2.67 cm and 20.0 cm, respectively. The downward force on the 2.67-cm piston that is required to lift a mass of 2000 kg supported by the 20-cm piston is

A) 350 N.
B) 270 N.
C) 36 N.
D) 1.5* 10³ N.
E) 2.6 * 10³ N.

Question 41

A beaker is filled with water. A ball of mass m and density $\rho$ < $\rho$ _water is tied to a string. The other end of the string is then tied to the bottom of the beaker so that the ball is completely submerged. When the string is cut, the acceleration of the ball is

A) .
B) .
C) g.
D) .
E) .

Question 42

A cylindrical piece of wood has a mass M = 0.235 kg. A small piece of lead with a mass m = 0.021 kg is fixed in the wood at the bottom of the cylinder so that the cylinder floats in water in a stable position, as shown. The radius of the cylinder is 1.65 cm. The depth x of the cylinder below the surface of the water is

A) 0.38 m.
B) 0.57 m.
C) 0.22 m.
D) 0.42 m.
E) 0.30 m.

Question 43

A large tub is half full of water. A mass M = 25.0 kg, which has a specific gravity of 2.5, is attached to the right-hand side of the tub, out of the water. The entire apparatus balances perfectly horizontally on a fulcrum at F, as in a). The tub is clamped in place and M is lowered to the bottom, completely submerged, as in b). When the clamps are removed, the tub

A) remains balanced.
B) tips, with point L going down.
C) tips, with point L going up.
D) starts oscillating.
E) behavior depends on mass and volume of mass M.

Question 44

A rock of mass M, that has a density equal to 150% that of water, is suspended in water by a thin, massless cord. The tension in the cord is

A) 2Mg.
B) Mg.
C) 4Mg.
D) zero.
E) 3Mg.

Question 45

A large spherical air balloon is filled with helium. If the balloon is to lift three people, each approximately 80 kg, plus a basket and balloon outer covering material of mass 50 kg, calculate the minimum radius of the balloon. Assume values of the density of air and helium to be 1.29 kg/m³ and 0.18 kg/m³ respectively.

A) 62 m
B) 8.0 m
C) 4.0 m
D) 20 m
E) 5.0 m

Question 46

You are floating in a boat in a swimming pool. The boat contains some blocks of wood. The specific gravity of the wood is 0.66. You throw the wood blocks into the pool. When the waves settle, the depth of the water in the pool

A) has increased.
B) is the same as before.
C) has decreased.
D) depends on the volume of the boat.
E) depends on the ratio of specific gravities of wood and boat.

Question 47

An adventurer builds a 1.80 m³ raft made out of cherry wood $\rho$ _CHERRY = 800 kg/m³) and places it in the seawater $\rho$ _SEAWATER = 1030 kg/m³). Determine the volume of the Styrofoam $\rho$ _STYROFOAM = 32.0 kg/m³) that would have to be attached to the bottom of the raft so only half of the raft's volume is submerged in the water.

A) 0.721 m³
B) 0.699 m³
C) 0.514 m³
D) 0.498 m³
E) 0.0072 m³

Question 48

A block of wood of mass 400 g and density 0.8 g/cm³ is floating on the surface of a liquid of density 1.3 g/cm³. What is the difference in mass of stone density = 1.9 g/cm³) that must be added to the block in order for the combination wood and stone) to be just submerged rather than only the wood to be submerged?

A) 250 g
B) 540 g
C) 170 g
D) 790 g
E) 290 g

Question 49

Two identical beakers are filled with the same amount of water. A ball of mass m is placed in the first beaker so that it floats on the surface while a second identical ball is placed in the second beaker but tied with a string of negligible mass so that the ball is completely submerged. Each beaker is then placed on a scale. Which scale has a higher reading?

A) a
B) b
C) the same
D) depends on how deep the ball is submerged in b
E) depends on the mass of the ball

Question 50

A cone with height h = 15.0 cm and bottom area of 7.85 × 10^-3 m² is placed in the container filled with seawater $\rho$ _SW = 1030 kg/m³) and oil $\rho$ _OIL = 790 kg/m³) so that the bottom of the cone is in seawater and its tip is in oil. What is the average density of the cone if the line between the fluids crosses through the midpoint between the bottom and the tip of the cone?

A) 820 kg/m³
B) 850 kg/m³
C) 910 kg/m³
D) 970 kg/m³
E) 1000 kg/m³

Question 51

A metal block suspended from a spring balance is submerged in water. You observe that the block displaces 55 cm³ of water and that the balance reads 4.3 N. What is the density of the block?

A) 7.0 g/ cm³
B) 8.0 g/cm³
C) 9.0 g/cm³
D) 1.1 g/cm³
E) 1.2 g/cm³

Question 52

A block of wood of mass 300 g and density 0.75 g/cm³ is floating on the surface of a liquid of density 1.1 g/cm³. What mass of lead density = 11.3 g/cm³) must be added to the block in order for the combination just to be submerged?

A) 440 g
B) 820 g
C) 140 g
D) 155 g
E) 25 g

Question 53

A rock of mass M with a density twice that of water is sitting on the bottom of an aquarium tank filled with water. The normal force exerted on the rock by the bottom of the tank is

A) 2Mg.
B) Mg.
C) Mg/2.
D) zero.
E) 3Mg.

Question 54

A raft of density 700 kg/m³ has a surface area of 7.0 m² and a volume of 0.7 m³. At what depth does it sink into water of density 1000 kg/m³?

A) 10 cm
B) 0.7 cm
C) 0.7 m
D) 7 m
E) 7 cm

Question 55

A beaker is filled with water. A small plastic container contains a solid bar of aluminum, which has a mass of 40 g, and is placed on the water so that it floats. The water level reads 60 ml. Next, the bar of aluminum is taken out of the container and placed in the water so that it sinks to the bottom. By how much does the water level change? Density of Al is 2.7 g/cm³.)

A) +40.0 ml
B) -40.0 ml
C) -25.2 ml
D) 0 ml
E) +25.2 ml

Question 56

A uniform cylinder of wood of length 25 cm is floating vertically upright in a dual layered fluid. An oil layer of density 0.90 g/cm³) that is 9.0 cm deep lies above a depth of water. If only 5.0 cm of wood lies above the oil surface, calculate the density of the wood.

A) 0.76 g/cm³
B) 0.80 g/cm³
C) 0.70 g/cm³
D) 0.66 g/cm³
E) 0.95 g/cm³

Question 57

A rock is thrown into a swimming pool that is filled with water at a uniform temperature. Which of the following statements is true?

A) The buoyant force on the rock is zero as it sinks.
B) The buoyant force on the rock increases as it sinks.
C) The buoyant force on the rock decreases as it sinks.
D) The buoyant force on the rock is constant as it sinks.
E) The buoyant force on the rock as it sinks is nonzero at first but becomes zero once the terminal velocity is reached.

Question 58

An object of irregular shape is placed into the container filled by glycerol $\rho$ _glycerol = 1250 kg/m³) and mineral oil $\rho$ _oil = 900 kg/m³). It sinks so that 60% of the object is submerged in glycerol. What is the density of the object?

A) 750 kg/m³
B) 1110 kg/m³
C) 1075 kg/m³
D) 1500 kg/m³
E) 1000 kg/m³

Question 59

You are floating in a boat in a swimming pool. There are some large stones, with a density of 2.5 g/cm³, in the boat. You throw the stones out of the boat and they sink to the bottom of the pool. The water level h, measured vertically at the end of the pool __________ as the stones are thrown out.

A) decreases
B) increases
C) changes depending on the ratio of V_rocks/ V_boat
D) stays the same
E) starts oscillating

Question 60

A block of wood of length L = 21.0 cm, width w = 9.53 cm, and height h = 5.92 cm is just barely immersed in water by placing a mass m on the top of the block. The density of the wood is $\rho$ = 0.390 g/cm³. The value of m is

A) 0.72 kg.
B) 7.1 kg.
C) 1.2 kg.
D) 1.6 kg.
E) 0.36 kg.

Question 61

Seawater of density 1.03 *10³ kg/m³ is in streamline flow through a Venturi meter. The pressure difference between the main pipe and the constriction is 20.7 kPa, and the flow velocity in the constriction is 7.32 m/s. The flow velocity in the main pipe is

A) 2.44 m/s.
B) 3.66 m/s.
C) 7.32 m/s.
D) 14.6 m/s.
E) 29.3 m/s.

Question 62

Bernoulli's equation for nonviscous flow can be stated as p₁ + $\rho$ gy₁ + $\rho$ v₁² = p₂ + $\rho$ gy₂ + $\rho$ v₂²
A fluid is flowing through a horizontal tube that changes in cross-sectional area from
A₁ = 0.75 cm² to A₂ = 0.030 cm². When v₁ = 3.5 cm/s, $\rho$ = 1.4 g/cm³, and viscosity is neglected, the difference between pressure p₂ at A₂ and p₁ at A₁ is

A) 54 *10³ dyn/cm², with P₁ higher.
B) 59 dyn/cm², with P₂ higher.
C) 59 dyn/cm², with P₁ higher.
D) 8.3 * 10² dyn/cm², with P₂ higher.
E) 5.4 * 10³ dyn/cm², with P₁ higher.

Question 63

Water is discharged from the tank in the manner shown. At which point is the pressure the smallest?

A) 1
B) 2
C) 3
D) 4
E) The pressure is the same at all points.

Question 64

A horizontal pipe of 30.0 cm² cross-sectional area carries water at a speed of 2.5 m/s. This pipe feeds a smaller pipe of cross section 10.0 cm². Find the speed of water flow in the smaller pipe.

A) 3.5 m/s
B) 0.8 m/s
C) 2.5 m/s
D) 7.5 m/s
E) 23 m/s

Question 65

The drag force on a plane is proportional to the density of the air. By what factor does the drag force change if a plane goes from an altitude 5.5 km to 11 km? The atmospheric pressure goes from to atm in going from 5.5 km to 11 km. Assume that the plane is at level flight and flies at the same speed.

A)
B)
C)
D) 1
E) 2

Question 66

A pipe of 2.54 cm inside diameter has a constriction in which the inside diameter is 1.27 cm. If water is flowing through this pipe with a velocity of 1.22 m/s in the main section, the velocity in the constricted section is

A) 0.305 m/s.
B) 0.610 m/s.
C) 2.44 m/s.
D) 1.22 m/s.
E) 4.88 m/s.

Question 67

Which conservation law governs the Bernoulli's equation?

A) Conservation of energy
B) Conservation of linear momentum
C) Conservation of angular momentum
D) Newton's universal law of gravitation
E) Conservation of electric charge

Question 68

A fish model that is 5.08 cm in diameter is placed in a pipe 25.4 cm in diameter and aligned along the axis of the pipe. If the water must flow past the fish at 2.44 m/s, the water in the unconstricted part of the pipe must flow at

A) 9.75 cm/s.
B) 2.84 m/s.
C) 2.35 m/s.
D) 2.44 m/s.
E) 6.10 m/s.

Question 69

A horizontal pipe narrows from a diameter of 10.0 to 5.0 cm. For a nonviscous fluid flowing from the larger diameter to the smaller,

A) the velocity and pressure both increase.
B) the velocity increases and the pressure decreases.
C) the velocity decreases and the pressure increases.
D) the velocity and pressure both decrease.
E) either the velocity or the pressure changes but not both.

Question 70

A tank is filled with water to a height H. A small hole is punched in one of the walls at a depth h below the water's surface. The water leaves the hole in a horizontal direction. The stream of water strikes the floor at a distance x, as shown. Neglecting viscosity, you can calculate the value of x from

A) x = H - h.
B) x = [2hH - h)]^1/2.
C) x = h.
D) x = 2[hH - h)]^1/2.
E) x = Hh/H-h).

Question 71

Water from a tap is flowing at a uniform rate of 24 cm³/s into a cylindrical container. An exit tube is mounted on the side of the container at height h/2 from the base. The height h of the water remains constant. The volume flow at which the water leaves the container is

A) 12 cm³/s.
B) 24 cm³/s.
C) 36 cm³/s.
D) 48 cm³/s.
E) 72 cm³/s.

Question 72

Cities across the U.S. supply fresh water to the residents at constant pressure by the use of water towers. If the diameter, d₂, of the pipe coming out of the tower is 25.0 cm, and the diameter, d₁, of the pipe at your home is 2.00 cm, what is the ratio of the velocity of the water at d₁ compared to d₂? Assume that all the taps are off except yours.

A) 12.5
B) 156
C) 0.0064
D) 0.08
E) 25

Question 73

Water flows at speed v in a pipe of radius r. Neglecting viscosity, at what speed does the water flow through a constriction in which the radius of the pipe is r/3?

A) v/9
B) v/3
C) v
D) 3v
E) 9v

Question 74

One statement of Bernoulli's law is: At any two points along a pipe in which there is a liquid in steady flow, the sum of the pressure, the kinetic energy per unit volume, and the potential energy per unit volume has the same value.For this statement to be true, it is not necessary to have

A) streamline flow.
B) frictionless flow.
C) an incompressible fluid.
D) fluid of constant density.
E) constant acceleration of the fluid between the two points.

Question 75

Seawater of density 1.03 *10³ kg/m³ is in streamline flow through a Venturi meter. The cross-sectional areas of the main pipe and the constriction are 0.139 m² and 0.0464 m², respectively, and the pressure difference between the two portions is 55.2 kPa. The velocity of flow in the main pipe is

A) 0.305 m/s.
B) 1.73 m/s.
C) 3.66 m/s.
D) 11.0 m/s.
E) 20.7 m/s.

Question 76

When Bernoulli's equation is written in the form p/ $\rho$ + v² + U = C,
The constant C represents the

A) energy per unit mass.
B) energy per unit volume.
C) net work done by outside forces.
D) power supplied by outside sources.
E) mass flow per unit time.

Question 77

A small portion of an incompressible liquid in steady flow through a pipe of variable cross section, if friction is negligible, has at each point throughout its path a constant

A) kinetic energy.
B) velocity.
C) potential energy.
D) total energy.
E) momentum.

Question 78

A wind with speed 45 m/s blows across a roof 20 m long and 12 m wide. The pressure inside the room is 1 atm. What is the net force on this roof due to the pressure difference inside and outside the roof? The density of air is equal to 1.3 kg/m³.)

A) 3.2 * 10⁵ N
B) 2.4 *10⁷ N
C) 6.3 * 10⁵ N
D) 7.0 * 10³ N
E) 3.2 * 10⁸ N

Question 79

An air-conditioning system is designed to fill a room of 10.0 m * 8.0 m * 6.0 m with fresh air every 20 minutes. If the circular air duct has a radius of 13 cm, calculate the speed of airflow in the duct.

A) 30.0 m/s
B) 450 m/s
C) 2.4 m/s
D) 7.5 m/s
E) 1.0 m/s

Question 80

The figure represents the streamline flow of an incompressible fluid. Which of the following statements is true of the velocity and/or pressure at the indicated points?

A) v_A = v_B = v_C
B) v_A = v_B = v_C; p_A $\neq$ p_B $\neq$ p_C
C) v_A $\neq$ v_B $\neq$ v_C; p_A = p_B = p_C
D) v_A $\neq$ v_B $\neq$ v_C; p_A $\neq$ p_B $\neq$ p_C
E) v_A = v_B = v_C; p_A > p_B > p_C