Preview Extract
Chapter 5 Fluid Mechanics
5.1 Density
1) If a loaf of bread is compressed, its
A) molecules decrease in size.
B) density decreases.
C) density increases.
D) none of the above
Answer: C
2) When a chocolate bar is cut in half, its density is
A) halved.
B) unchanged.
C) doubled.
Answer: B
3) Compared to a bar of pure gold, the density of a pure gold ring is
A) less.
B) the same.
C) more.
Answer: B
4) Which has the greater density, a lake full of water or a cupful of lake water?
A) the cupful of lake water
B) the lake
C) both have the same density
Answer: C
5) Compared to the density of a kilogram of feathers, the density of a kilogram of lead is
A) less.
B) more.
C) the same.
Answer: B
6) If the mass of an object were to double with no change in volume, its density would
A) be half.
B) double.
C) unchanged.
Answer: B
7) If the volume of an object were to double with no change in mass, its density would
A) be half.
B) double.
C) unchanged.
Answer: A
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8) The density of air at room temperature is about 1.2 grams/cm . This is the same as
3
A) 12 kg/m .
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B) 120 kg/m .
3
C) 1200 kg/m .
Answer: C
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9) The density of air at room temperature is about 1.2 grams/cm . Estimate the mass of air inside
an average automobile.
A) 2 grams
B) 2 kg
C) 20 kg
D) 200 kg
E) 2000 kg
Answer: B
5.2 Pressure
1) When you stand on tiptoes on a bathroom scale, there is an increase in
A) weight reading.
B) pressure on the scale, not registered as weight.
C) both weight and pressure on the scale.
D) none of the above
Answer: B
2) Water pressure at the bottom of a lake depends on the
A) weight of water in the lake.
B) surface area of the lake.
C) depth of the lake.
D) all of the above
Answer: C
3) The pressure in a liquid depends on liquid
A) density.
B) depth.
C) both
D) neither
Answer: C
4) Consider two tubes filled with water at the same height, one with fresh water and the other
tube with salt water. The pressure is greater at the bottom of the tube with
A) fresh water.
B) salt water.
C) both the same
D) depends on whether the tubes have the same cross-sectional area.
Answer: B
5) Water pressure is greatest against the
A) top of a submerged object.
B) bottom of a submerged object.
C) sides of a submerged object.
D) same against all surfaces.
E) none of the above
Answer: B
6) A dam is thicker at the bottom than at the top because
A) water is denser at deeper levels.
B) water pressure is greater at deeper levels.
C) water is cooler at deeper levels.
D) dams look better.
E) none of the above
Answer: B
7) The pressure at the bottom of a jug filled with water does NOT depend on
A) the acceleration due to gravity.
B) water density.
C) the height of the liquid.
D) surface area of the water.
E) none of the above
Answer: D
8) Blood pressure is normally greater in your
A) ears.
B) feet.
C) same in each.
Answer: B
9) As a swimmer dives deeper and deeper, strictly speaking, the volume of water displaced by
the swimmer actually
A) decreases.
B) increases.
C) remains unchanged but pressure on her increases.
D) none of the above
Answer: A
10) As a woman holding her breath swims deeper and deeper in a lake, her density
A) increases.
B) decreases.
C) remains the same.
Answer: A
11) There is a legend of a Dutch boy who bravely held back the Atlantic Ocean by plugging a
leak near the top of a dike with his finger until help arrived. Which of the following is most
likely?
A) the huge size of the Atlantic Ocean makes this impossible
B) force on his finger would be huge but pressure small enough
C) the force on his finger would have been less than 1 N
D) both the force and pressure on his finger would have been huge, but not too huge for a publicspirited Dutch lad
E) none of the above
Answer: C
12) Clearly distinguish between pressure and force in the case of weighing yourself on a
common bathroom scale.
Answer: By definition, pressure is the ratio of force per unit area. We can think of a force as a
push on a surface, like the force due to gravity you exert on a bathroom scale when you stand on
it. Pressure is the distribution of this force. The scale measures force, not pressure, so your
weight reading is the same no matter how you distribute your weight on the scale. With your
weight on one foot instead of two, pressure on the supporting surface is twice the pressure when
you stand on two feet. But the scale reading, which reads force only, is the same.
13) Fill a U-tube with water and the level in both ends is the same. Water seeks its own level.
Why?
Answer: The water in one side of the filled U-tube pushes water up the other side until the
pressure in both sides is equal. Movement of water at the bottom of the tube stops when pressure
is the same from each tube. And because water pressure is dependent on depth, the equal
pressures at the bottom correspond to equal depths of water in each side.
5.3 Buoyancy in a Liquid
1) One liter of water has a mass of
A) 1 kg.
B) 1 N.
C) both
D) neither
Answer: A
2) Pumice is a volcanic rock that floats. Compared with the density of water, its density is
A) less.
B) the same.
C) more.
Answer: A
3) A completely submerged object always displaces its own
A) volume of fluid.
B) weight of fluid.
C) density of fluid.
D) all of the above
E) none of the above
Answer: A
4) A fish normally displaces its own
A) volume of water.
B) weight of water.
C) both
D) neither
Answer: C
5) Compared to the density of water, the density of a fish is
A) more.
B) less.
C) the same.
Answer: C
6) Wood from the Lignum vitae tree in South America is denser than water. Could a boat be
made with this wood? A raft? Briefly explain.
Answer: Yes, a boat could easily be made of this wood. Boats are made of iron, and barges are
made of concrete, so why not? The important factor is shaping the vessel so it can displace its
own weight of water when floating. A raft is a different story. Unless it's shaped like a bowl or
boat, the raft will sink.
7) What is the approximate density of a fish, compared with the density of water? Defend your
answer.
Answer: The density of a fish is the same as the density of the water in which it swims. If the fish
were more dense, it would sink in the water. If the fish is less dense, it would float. The fact that
a fish neither floats nor sinks is evidence that its density matches that of water.
5.4 Archimedes' Principle
1) Buoyant force acts upward on a submerged object because
A) it acts in a direction to oppose gravity.
B) if it acted downward, nothing would float.
C) the weight of fluid displaced reacts with an upward force.
D) pressure up on bottom is greater than downward pressure on top of the object.
Answer: D
2) What is the buoyant force acting on a 10-ton ship floating in the ocean?
A) less than 10 tons
B) 10 tons
C) more than 10 tons
D) depends on density of seawater
Answer: B
3) What is the buoyant force acting on a 10-ton ship floating in a fresh-water lake?
A) less than 10 tons
B) 10 tons
C) more than 10 tons
D) not enough information
Answer: B
4) What is the weight of water displaced by a 100-ton floating ship?
A) less than 100 tons
B) 100 tons
C) more than 100 tons
D) 100 cubic meters
E) depends on the ship's shape
Answer: B
5) When an object is partly or wholly immersed in a liquid, it is buoyed up
A) by a force equal to its own weight.
B) by a force equal to the weight of liquid displaced.
C) and floats because of Archimedes' principle.
D) but sinks.
E) none of the above
Answer: B
6) The buoyant force on an object is less when the object is
A) partly submerged.
B) submerged near the surface.
C) submerged near the bottom.
D) none of the above
Answer: A
7) The reason a life jacket helps you float is that
A) the jacket causes you to weigh less.
B) the jacket has the same density as an average human.
C) the jacket repels water.
D) if you sink, the jacket sinks.
E) the combined density of you and the jacket is less than your density alone.
Answer: E
8) Lobsters live on the bottom of the ocean. Compared with the density of seawater, the density
of a lobster is
A) greater.
B) the same.
C) less.
Answer: A
9) A lobster crawls onto a bathroom scale submerged on the ocean bottom. Compared to its
weight above the surface, its apparent weight under water is
A) greater.
B) less.
C) the same.
Answer: B
10) Two life preservers have identical volumes, one filled with Styrofoam and the other filled
with sand. When both life preservers are fully submerged, the buoyant force is greater on the one
filled with
A) Styrofoam.
B) sand.
C) same on each if volumes remain the same.
Answer: C
11) The density of a submarine cruising beneath the ocean surface has the same density as
A) a crab.
B) iron.
C) a floating submarine.
D) water.
E) none of the above
Answer: D
12) A rock suspended by a weighing scale weighs 3 N when submerged in water and 5 N out of
water. What is the buoyant force on the rock?
A) 8 N
B) 5 N
C) 3 N
D) 2 N
E) none of the above
Answer: D
13) An egg is placed at the bottom of a bowl filled with water. Salt is slowly added to the water
until the egg rises and floats. From this experiment, we conclude that
A) egg-shell calcium is repelled by sodium chloride.
B) the density of salt water exceeds the density of the egg.
C) buoyant force does not always acts upward.
D) salt sinks to the bottom.
E) none of the above
Answer: B
14) Ice cubes submerged at the bottom of a liquid mixture indicate that the mixture
A) fails to produce a buoyant force on the ice.
B) has dissolved air in a liquid state.
C) is composed of open-structured crystals.
D) is less dense than ice.
Answer: D
15) When a 5-N block of wood floats in mercury the buoyant force on it is
A) less than 5 N.
B) 5 N.
C) more than 5 N.
Answer: B
16) The volume of water displaced by a floating 20-ton boat is
A) 20 cubic meters.
B) the volume of 20 tons of water.
C) the volume of the boat.
D) depends on the shape of the ship's hull.
E) none of the above
Answer: B
17) Compared with an empty ship, the same ship loaded with Styrofoam will float
A) higher in the water.
B) lower in the water.
C) at the same level in the water.
Answer: B
18) Two equal-sized buckets are filled to the top with water. One of the buckets has a piece of
wood floating in it, making its total weight
A) less than the weight of the other bucket.
B) equal to the weight of the other bucket.
C) more than the weight of the other bucket.
Answer: B
19) The pair of water-filled caissons of the Falkirk Wheel have equal weights when
A) they carry equal-weight floating boats.
B) one carries a heavy floating boat and the other only water.
C) they carry unequal weights of floating boats.
D) all of the above
E) none of the above
Answer: D
20) If one of the caissons of the Falkirk Wheel contained a sunken boat, resting on its bottom,
and the other carried a floating boat, the wheel balance would
A) still be maintained.
B) be upset and more energy would be needed for operation.
C) render the machine useless.
D) violate Archimedes' principle.
Answer: B
21) If one caisson of the Falkirk Wheel carries a boat loaded with Styrofoam and the other
carries a floating boat loaded with iron, the wheel would be
A) balanced.
B) out of balance.
C) unbalanced but still useful.
D) useless for lifting boats.
Answer: B
22) A block of Styrofoam floats on water while a same size block of lead lies submerged in the
water. The buoyant force is greatest on the
A) lead.
B) Styrofoam.
C) same for both
Answer: A
23) A liter-sized block of ordinary wood floats in water. The volume of water displaced is
A) less than 1 L.
B) 1 L.
C) more than 1 L.
D) none of the above
Answer: A
24) Buoyant force is greatest on a submerged 1 cubic centimeter block of
A) lead.
B) aluminum.
C) same on each
Answer: C
25) Buoyant force is greatest on a submerged
A) 1-kg block of lead.
B) 1-kg block of aluminum.
C) same on each
Answer: B
26) Buoyant force is greatest on a submerged
A) 10-N block of lead.
B) 10-N block of aluminum.
C) same on each
Answer: B
27) When a boat sails from fresh water to salt water, the boat will float
A) lower in the water.
B) higher in the water.
C) at the same water level.
Answer: B
28) Two life preservers have identical volumes, one filled with Styrofoam and the other filled
with sand. When each is worn by swimmers, one swimmer floats and the other sinks.
Interestingly, the buoyant force is actually greater on the life preserver that
A) sinks.
B) floats.
C) same either way
D) none of the above
Answer: A
29) An iron ball is placed in a pie pan that floats in a bucket. The water level is marked at the
side of the bucket. Then the iron ball is removed and allowed to sink in the bucket. The water
line at the side of the bucket is
A) lower.
B) the same.
C) higher.
Answer: A
30) A boat loaded with scrap iron floats in a swimming pool. When the iron is thrown overboard,
the pool level will
A) rise.
B) fall.
C) remain unchanged.
Answer: B
31) A boat loaded with a barrel of water floats in a swimming pool. When the barrel of water is
poured overboard, the pool level
A) rises.
B) falls.
C) remains unchanged.
Answer: C
32) A boat loaded with wood floats in a swimming pool. When the wood is thrown overboard,
the pool level
A) rises.
B) falls.
C) remains unchanged.
Answer: C
33) If a battleship sinks in a canal lock, the water level in the lock
A) rises.
B) falls.
C) remains unchanged.
Answer: B
34) If the part of an iceberg that extends above the water were suddenly removed, the
A) iceberg would sink.
B) buoyant force on the iceberg would soon decrease.
C) density of the iceberg would change.
D) pressure on the bottom of the iceberg would increase.
E) none of the above
Answer: B
35) If a weighted air-filled balloon sinks in deep water, it will
A) likely sink to an equilibrium level before reaching the bottom.
B) likely burst if water pressure is great enough.
C) become less dense as it sinks.
D) be acted on by a continually decreasing buoyant force.
E) none of the above
Answer: D
36) When an ice cube in a glass of water melts, the water level
A) rises.
B) falls.
C) remains the same.
Answer: C
37) An ice cube that contains small pieces of iron floats on water. When the ice melts, the water
level
A) rises.
B) falls.
C) remains unchanged.
Answer: B
38) An ice cube floating in a glass of water contains many air bubbles. When the ice melts, the
water level
A) rises.
B) falls.
C) remains unchanged.
Answer: C
39) Three large ice cubes float in bathtubs, each filled to the brim with water. Cube A has large
air bubbles in it. Cube B has unfrozen water in it. Cube C has an iron railroad spike in it. When
the ice cubes melt
A) water level in C decreases while water levels in the other two tubs remain the same.
B) only the water in C will spill over.
C) water level in A remains unchanged while the other tubs spill over.
D) all tubs spill over.
E) all levels remain the same.
Answer: A
40) A wooden block with a piece of iron tied to its top floats in a bucket of water. If the wood
and iron flips over so the iron is on the bottom, the water level at the side of the bucket
A) rises.
B) falls.
C) remains the same.
Answer: C
41) Compared to the buoyant force on you when floating in fresh water, buoyant force on you
when floating in the dense water of the Dead Sea is
A) less because volume displacement is less.
B) more because of the greater density of fluid displaced.
C) the same.
Answer: C
42) Explain why ships of any weight are balanced on the Falkirk Wheel.
Answer: The levels of water in the two Falkirk caissons are the same whether a boat floats in
them or not. As Figure 5.16 in the textbook shows, the weight of the container will be the same
no matter what the weight of the object(s) floating in it. The floating object displaces a weight of
water equal to its own weight. Hence the two caissons weigh the same and are balanced.
43) Explain in terms of buoyant force how a fish is able to rise and sink in water. Contrast this to
the way a submarine rises and sinks.
Answer: To rise or sink, a fish expands or contracts by means of an air bladder. When the
bladder expands, and the volume of the fish increases, the fish displaces more water. This
increases the buoyant force and the fish rises. The opposite occurs when the fish contracts its air
bladder, decreased volume is accompanied by decreased buoyant force, and the fish sinks.
A submarine accomplishes the same by varying its weight. When water is taken into its tanks,
the submarine is heavier. If it is heavier than the buoyant force, it sinks. When water is ejected
from its tanks, the submarine becomes lighter. If the submarine is lighter than the buoyant force,
it rises.
44) We know that any body more dense than water will sink in water. Why?
Answer: If a body is more dense than water, it will be heavier than an equal volume of water.
This means the downward force of gravity will exceed the upward buoyant force that acts on it.
Net force will be downward, hence the body sinks.
5.5 Pressure in a Gas
1) In a vacuum, a marshmallow becomes
A) larger.
B) smaller.
C) does not change.
Answer: A
2) The product of gas pressure and volume for a given mass of gas is constant
A) if the temperature doesn't change.
B) whether or not temperature changes.
C) never.
D) none of the above
Answer: A
3) When gas in a container is squeezed to half its volume, its density
A) halves.
B) doubles.
C) quadruples.
D) remains the same.
Answer: B
4) When gas in a container expands to twice its volume, its density
A) is half.
B) doubles.
C) quadruples.
D) remains the same.
Answer: A
5) When gas in a container is squeezed to half its volume at constant temperature, the gas
pressure
A) is half.
B) doubles.
C) quadruples.
D) remains the same.
Answer: B
6) When gas in a container expands to twice its volume at constant temperature, the gas pressure
A) is half.
B) doubles.
C) quadruples.
D) remains the same.
Answer: A
7) Strictly speaking, gas pressure inside an inflated stretched balloon is
A) less than air pressure outside the balloon.
B) equal to air pressure outside the balloon.
C) slightly greater than air pressure outside the balloon.
Answer: C
8) How deep must an inverted drinking glass be pushed beneath the surface of water so that the
volume of enclosed air is squeezed to half?
A) 76 cm
B) 10.3 m
C) 14.7 m
D) 20.6 m
E) 29.4 m
Answer: B
9) A swimmer cannot snorkel more than a meter deep because air
A) in the lungs cannot be easily expelled.
B) tends to liquefy in the snorkel tube.
C) is buoyed up leaving the swimmer breathless.
D) at the surface will not freely enter the higher-pressure region in the compressed lungs.
E) all of the above
Answer: D
5.6 Atmospheric Pressure
1) Atmospheric pressure is caused by the
A) density of the atmosphere.
B) weight of the atmosphere.
C) temperature of the atmosphere.
D) effect of the Sun's energy on the atmosphere.
Answer: B
2) What is the approximate mass of a 1-square centimeter column of air that extends from sea
level to the top of the atmosphere?
A) 1 g
B) 1 kg
C) 10 kg
D) 100 kg
Answer: B
3) The air in this room has
A) mass.
B) weight.
C) energy.
D) all of the above
E) none of the above
Answer: D
4) When a suction cup sticks to a wall it is
A) pulled to the wall by the vacuum.
B) pushed to the wall by the atmosphere.
C) both
D) neither
Answer: B
5) How high can water be theoretically lifted by a vacuum pump at sea level?
A) less than 10.3 m
B) 10.3 m
C) more than 10.3 m
Answer: B
6) A barometer can be made with water. Compared with a mercury barometer, the column height
for a water barometer would be
A) shorter.
B) the same.
C) higher.
Answer: C
7) Compared with a mercury barometer, the column height for an alcohol barometer would be
A) shorter.
B) the same.
C) higher.
Answer: C
8) A column of contained air extends from sea level to the top of the atmosphere. The contained
air has mass. If the column instead contained the same mass of water, its height would be
A) 1/13.6 times as high as the atmosphere.
B) about 3/4 m high.
C) 10.3 m high.
D) about 5.6 km high.
Answer: C
9) Consider two mercury barometers, one with twice the cross-section area of the other. Mercury
in the wider tube will rise
A) to the same height as in the narrow tube.
B) twice as high as mercury in the narrow tube.
C) four times as high as mercury in the narrow tube.
D) more than four times as high as in the narrow tube.
E) none of the above
Answer: A
10) Consider two vertical tubes of equal cross-section area, one containing water and the other
mercury. If the liquid pressures at the bottom of the tubes are equal, both liquids would have
equal
A) volumes.
B) densities.
C) weights.
D) number of molecules.
E) none of the above
Answer: C
11) It would be easier to pull evacuated Magdeburg hemispheres apart if they were
A) held upside down.
B) at sea level.
C) 2 km beneath the ocean surface.
D) 2 km above the ocean surface.
E) none of the above
Answer: D
5.7 Pascal's Principle
1) A change in pressure at any point in a confined fluid at rest is transmitted
A) undiminished to all points in the fluid.
B) to points of lower pressure.
C) in the direction of lower energies.
D) all of the above
E) none of the above
Answer: A
2) An important underlying feature of hydraulic devices is the conservation of
A) pressure.
B) momentum.
C) energy.
D) all of the above
E) none of the above
Answer: C
3) If a pressure of 20 kPa is applied to one piston in a simple hydraulic device, the pressure on a
piston of larger area will be
A) less than 20 kPa.
B) the same 20 kPa.
C) more than 20 kPa.
D) all of the above
E) none of the above
Answer: B
4) A hydraulic device has two pistons, one with a small cross-section area and another piston
with a larger cross-section area. If a given force is applied to the small piston, the output force on
the larger-area piston will be
A) less.
B) the same.
C) more.
D) all of the above
E) none of the above
Answer: C
5) Very importantly, a hydraulic press can multiply
A) forces.
B) pressures.
C) energy.
D) all of the above
E) none of the above
Answer: A
5.8 Buoyancy in a Gas
1) A rising balloon is buoyed up with a force equal to the
A) weight of air it displaces.
B) density of surrounding air.
C) atmospheric pressure.
D) weight of the balloon and its contents.
E) all of the above
Answer: A
2) A 1-ton blimp hovers in air. The buoyant force acting on it is
A) zero.
B) 1 ton.
C) less than 1 ton.
D) more than 1 ton.
Answer: B
3) As a helium-filled balloon rises in the air, it becomes
A) bigger.
B) more dense.
C) heavier.
D) all of the above
E) none of the above
Answer: A
4) A bubble of air released from the bottom of a lake
A) rises to the top at constant volume.
B) becomes smaller as it rises.
C) becomes larger as it rises.
D) alternately expands and contracts as it rises.
E) none of the above
Answer: C
5) In a vacuum, an object has no
A) buoyant force.
B) mass.
C) weight.
D) temperature.
E) all of the above
Answer: A
6) A common 5-L metal can will float in air if it is
A) evacuated of air.
B) filled with a very large amount of helium.
C) thrown high enough into the air.
D) Nonsense! Unless the can and displaced air weigh the same, the can can't float in air.
Answer: D
7) As a high-altitude balloon sinks lower and lower into the atmosphere it undergoes a decrease
in
A) volume.
B) density.
C) weight.
D) mass.
E) none of the above
Answer: A
8) Compared with the buoyant force of the atmosphere on a 1-L helium-filled balloon, the
buoyant force of the atmosphere on a nearby 1-L solid iron block is
A) considerably less.
B) considerably more.
C) the same.
Answer: C
9) Compared with the buoyant force of the atmosphere on a 1-kg helium-filled balloon, the
buoyant force of the atmosphere on a nearby 1-kg solid iron block is
A) considerably less.
B) considerably more.
C) the same.
Answer: A
10) Suppose you stand on a weighing scale and all of a sudden the atmosphere vanishes. The
reading on the scale would
A) increase.
B) decrease.
C) remain the same.
Answer: A
11) A large block of wood and a small block of iron each register 2000 N on a weighing scale.
Taking buoyancy of air into account, which has the greater mass?
A) wood
B) iron
C) both the same
Answer: A
12) An empty jar is pushed open side downward into water so that air trapped inside can't
escape. As it is pushed deeper, the buoyant force on the jar
A) increases.
B) decreases.
C) remains the same.
Answer: B
13) Why will a helium-filled balloon rise in air while an air-filled balloon sinks?
Answer: Both balloons displace air and have a buoyant force that depends on their volumes. If
buoyancy were the only force acting, they both would rise, but there's weight. The air-filled
balloon is simply heavier than the air it displaces, thus its weight is greater than the buoyant
force, and it sinks. It is heavier because the stretched balloon fabric compresses the air within.
Likewise for the helium, but it is so low in density that even when compressed it is still lighter
than the air it displaces.
14) Which is greater, the buoyant force that acts on an elephant, or on a helium-filled party
balloon? Explain then, why the balloon rises in air and the elephant doesn't.
Answer: The buoyant force exerted by the atmosphere is equal to the weight of air displaced.
Since an elephant has more volume, it displaces more air and has a greater buoyant force on it
than does the smaller helium-filled balloon. But whether or not something rises has to do with
the relative magnitudes of the buoyant force and the force of gravity. Aha, the force of gravity on
the elephant is enormously greater than the buoyant force on the elephant. So gravity wins and
the elephant is pressed to the surface. But for the balloon, its weight is less than the small
buoyant force on the balloon. Buoyant force wins and the balloon rises.
5.9 Bernoulli's Principle
1) As water in a confined pipe speeds up, the pressure it exerts against the inner walls of the pipe
A) increases.
B) decreases.
C) remains constant if flow rate is constant.
D) none of the above
Answer: B
2) If air speed is greater along the top surface of a bird's wings, pressure of the moving air there
is
A) unaffected.
B) less.
C) more.
D) turbulent.
Answer: B
3) Airplane lift is achieved when air pressure on the bottom of a wing is
A) greater than pressure on top.
B) less than pressure on top.
C) the same as pressure on top.
Answer: A
4) An umbrella tends to jerk upward on a windy day principally because
A) air gets trapped under the umbrella, warms, and rises.
B) buoyancy increases with increasing wind speed.
C) air pressure is reduced over the curved top surface.
D) all of the above
Answer: C
5) Wind blowing over the top of a hill
A) increases atmospheric pressure there.
B) decreases atmospheric pressure there.
C) does not affect atmospheric pressure there.
Answer: B
6) The Bernoulli effect causes passing ships to be drawn together when the ships are close and
moving in
A) the same direction.
B) the opposite direction.
C) either the same or opposite direction.
Answer: C
7) Suspend a pair of Ping-Pong balls from two strings so there is a small space between them. If
you blow air between the balls, they will swing
A) toward each other.
B) apart from each other.
C) away from the airstream, but not necessarily toward or apart from each other.
Answer: A
8) Why is an umbrella in danger of being turned inside out on a windy day?
Answer: Because of the umbrella's curvature, air passes faster over its top than across its bottom.
This produces a difference in forces, and like an airplane wing, experiences lift. This is in accord
with Bernoulli's principle. The lift can turn or flip the umbrella inside out.
Test Bank for Conceptual Physical Science
Paul Hewitt, John Suchocki, Leslie Hewitt
9780321752932, 9780134060491
