Deck 5: Fluid Mechanics

Question 1

Compared to a bar of pure gold,the density of a pure gold ring is

A)less.
B)the same.
C)greater.

Answer 1

B

Question 2

While you are standing,your blood pressure is normally greatest in your

A)head.
B)heart.
C)feet.
D)same in each

Answer 2

C

Question 3

Compared to the density of a kilogram of feathers,the density of a kilogram of lead is

A)less.
B)greater.
C)the same.

Answer 3

B

Question 4

The density of air at room temperature is about 1.2 g/cm³.This is the same as

A)12 kg/m³.
B)120 kg/m³.
C)1200 kg/m³.

Question 5

If the volume of an object doubles with no change in mass,its density would be

A)half.
B)double.
C)unchanged.

Question 6

Which will remain the same for two identical books,one lying flat and the other standing on an end?

A)weight only
B)pressure only
C)both pressure and weight
D)none of the above

Question 7

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

Question 8

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

Question 9

The pressure in a liquid depends on liquid

A)density.
B)depth.
C)both of these
D)none of the above

Question 10

Two identical tubes are filled with water,one with fresh water and one 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

Question 11

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

Question 12

When a loaf of bread is compressed,its

A)molecules decrease in size.
B)density decreases.
C)density increases.
D)none of the above

Question 13

If we double the mass of an object without a change in volume,its density would be

A)half.
B)double.
C)unchanged.

Question 14

The concept of pressure involves both

A)force and volume.
B)force and area.
C)area and volume.

Question 15

Your density is slightly greater when you are

A)at the top of a mountain.
B)submerged deep in water.
C)in a fast-moving vehicle.
D)none of the above

Question 16

If you lie on a bed of nails your back will encounter pressure due to contact with the nails.Nail pressure on your back will be less if the bed has

A)fewer nails.
B)more nails.
C)both of the above
D)none of the above

Question 17

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

Question 18

Water pressure on a submerged object is greatest against its

A)top.
B)bottom.
C)sides.
D)same against all surfaces
E)none of the above

Question 19

The density of air at room temperature is about 1.2 g/cm³.Estimate the mass of air inside a 0.80-m³ volume refrigerator.(There are 1 million cm³ in 1 m³.)

A)0.96 g
B)960 kg
C)1000 kg
D)more than 1000 kg

Question 20

When a chocolate bar is cut in half,its density of each half is

A)halved.
B)unchanged.
C)doubled.

Question 21

The buoyant force that acts on a 10-ton ship floating in the ocean is

A)less than 10 tons.
B)10 tons.
C)greater than 10 tons.
D)depends on the density of seawater

Question 22

As a person holding her breath swims deeper and deeper in a lake,her density

A)increases.
B)decreases.
C)remains the same.

Question 23

A flask half filled with water is on a weighing scale.If you float a piece of wood in it,the scale reading will be

A)less.
B)the same.
C)greater.

Question 24

A fish normally displaces its own

A)volume of water.
B)weight of water.
C)both of these
D)none of the above

Question 25

Buoyant force is greatest on a submerged 1-cm³ block of

A)lead.
B)aluminum.
C)same on each

Question 26

One liter of water has a mass of

A)1 kg.
B)1 N.
C)both of these
D)none of the above

Question 27

The buoyant force that acts on a submerged object is equal to

A)the object's weight.
B)the object's volume.
C)both the weight and volume of the object.
D)the weight of water it displaces.

Question 28

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 against its bottom is greater than pressure against its top.

Question 29

The block that displaces the greatest volume of water when submerged is a

A)1-kg block of aluminum.
B)1-kg block of iron.
C)1-kg block of lead.
D)all the same

Question 30

A flask half filled with water is on a weighing scale.If you suspend a stone by a string into the water the scale reading will be

A)less.
B)the same.
C)greater.

Question 31

The buoyant force on an object is less when the object is

A)only partly submerged.
B)submerged near the surface.
C)submerged near the bottom.
D)none of the above

Question 32

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)The force on his finger would be huge but the 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.
E)none of the above

Question 33

When holes are drilled through the wall of a water tower,water will spurt out with the greatest speed from the hole closest to the

A)bottom of the tower.
B)middle of the tower.
C)top of the tower.
D)all the same

Question 34

A block of Styrofoam floats on water while a same-size lead block lies submerged in the water.The buoyant force is greatest on the

A)lead.
B)Styrofoam.
C)same for both

Question 35

A flask brim filled with water is on a weighing scale.If you float a piece of wood in it,after spillage away from the scale,the scale reading will be

A)less.
B)the same.
C)greater.

Question 36

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

Question 37

Compared to the density of water,the density of a fish is

A)greater.
B)less.
C)the same.

Question 38

Buoyant force is greatest on a submerged

A)10-N block of lead.
B)10-N block of aluminum.
C)same on each

Question 39

Buoyant force is greatest on a submerged

A)1-kg block of lead.
B)1-kg block of aluminum.
C)same on each

Question 40

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

Question 41

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

Question 42

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.

Question 43

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

Question 44

A key feature of the Falkirk Wheel in Scotland is that opposite caissons have the same weight when both are brim-full of water

A)and boats in each have about equal weights.
B)and at least one boat is in each caisson.
C)regardless of the weights of boats or no boats in each.
D)none of the above

Question 45

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)greater than 5 N.

Question 46

Two equal-sized buckets are brim-filled with water,one with a piece of floating wood and the other without.If the buckets are put on a weighing scale,the heavier one is

A)the bucket with the floating wood.
B)the bucket without the wood in it.
C)either,for the weights of both are the same.

Question 47

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.

Question 48

How much buoyant force acts 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

Question 49

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)ocean water.
E)none of the above

Question 50

A lobster crawls onto a bathroom scale submerged on the ocean bottom.Compared to its weight above the surface,its weight under water is

A)greater.
B)less.
C)the same.

Question 51

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 is not always exerted upward.
D)salt sinks to the bottom.
E)none of the above

Question 52

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.

Question 53

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 density of water

Question 54

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.

Question 55

The pair of water-filled caissons of the Falkirk Wheel have equal weights whenever

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

Question 56

The fact that the weight of a brim-full container of water is unchanged whether or not something floats in it is nicely employed in

A)hydraulic devices.
B)all floating devices.
C)Scotland's Falkirk Wheel.
D)none of the above

Question 57

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

Question 58

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.

Question 59

An important condition for the operation of the Falkirk Wheel is that

A)water in each caisson have the same depth.
B)ships carried are more or less equal in weight.
C)no water spill when a ship enters a caisson.
D)all of the above
E)none of the above

Question 60

A liter-sized block of wood floats in water.The volume of water displaced is

A)less than 1 L.
B)1 L.
C)greater than 1 L.
D)none of the above

Question 61

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.

Question 62

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

Question 63

A marshmallow in a vacuum becomes

A)larger.
B)smaller.
C)does not change.

Question 64

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.

Question 65

Greta and her family float higher in the dense water of the Dead Sea because

A)less volume of water is displaced.
B)more volume of water is displaced.
C)of a greater buoyant force.

Question 66

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

Question 67

If a battleship sinks in a canal lock,the water level in the lock

A)rises.
B)falls.
C)remains unchanged.

Question 68

Life jackets help you float because

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.

Question 69

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.

Question 70

When an ice cube in a glass of water melts,the water level

A)rises.
B)falls.
C)remains the same.

Question 71

Two life preservers have identical volumes,one filled with Styrofoam and the other filled with sand.When both 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.

Question 72

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.

Question 73

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.

Question 74

A flat piece of iron is tightly tied against top of a wooden block.The iron-wood block floats in a bucket of water.If the iron-wood block 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.

Question 75

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 the temperature changes.
C)never.
D)none of the above

Question 76

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

Question 77

When you float in fresh water,the buoyant force that acts on you is equal to your weight.When you float higher in the denser water of the Dead Sea,the buoyant force that acts on you is

A)greater than your weight.
B)less than your weight.
C)equal to your weight.

Question 78

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.

Question 79

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.

Question 80

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.