Physics: A Conceptual World View

Larry D. Kirkpatrick, Gregory E. Francis

Chapter 12 States of Matter - all with Video Answers

Educators

Chapter Questions

00:15

Problem 1

What are the four states of matter?

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00:42

Problem 2

Is the average kinetic energy of the molecules in a liquid greater or smaller than in a solid of the same material? Why?

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00:35

Problem 3

Does the aluminum in a soda can or in an automobile engine have the larger density? Why?

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00:25

Problem 4

Which has a greater density, a tiny industrial diamond used in grinding powders or a 3 -carat diamond in a wedding ring? Explain.

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00:54

Problem 5

Aluminum and magnesium have densities of 2.70 and 1.75 grams per cubic centimeter, respectively. If you have equal masses of each, which one will occupy the larger volume? Explain.

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01:08

Problem 6

Gold and silver have densities of 19.3 and 10.5 grams per cubic centimeter, respectively. If you have equal volumes of each, which one will have the larger mass? Explain.

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01:39

Problem 7

Although the uranium atom is more massive than the gold atom, gold has the larger density. What does this tell you about the two solids?

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00:59

People who live in cold climates know better than to turn off the heat in their homes in the winter without first draining the water out of the copper pipes. Explain why the pipes will burst if this is not done.

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00:54

Problem 9

Are the crystal structures of ice and table salt the same? How do you know?
(picture cannot copy)

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00:48

Problem 10

How does the crystal structure of mica differ from that of table salt?

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00:34

Problem 11

How does the structure of diamond differ from that of graphite?

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00:35

Problem 12

What does the observation that mica can be separated into thin sheets tell you about the crystal structure of mica?

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00:55

Problem 13

When solids melt to form liquids, they retain their chemical identity. Which is stronger, the forces holding atoms together to form molecules or the forces holding the molecules together in a solid? Why?

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01:04

Problem 14

Which is stronger in a typical liquid, the inter molecular forces (those between molecules) or the interatomic forces (those holding the molecule together)? What evidence do you have for your answer?

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01:07

Problem 15

What shape would you expect a drop of water to take if it were suspended in the air in the space shuttle?

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00:37

Problem 16

Why does water bead up when it is spilled on a waxed floor?

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01:00

Problem 17

If you fill a glass with water level with the top of the glass, you can carefully drop several pennies into the glass without spilling any water. How do you explain this?
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00:49

Problem 18

Why does soapy water bead up less than plain water on a counter top?

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00:40

Problem 19

When you half-fill a glass with water, the water creeps up where it meets the glass. What can you conclude about the relative strengths of the inter molecular forces between the water molecules and the adhesive forces between the water molecules and the glass?

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00:38

Problem 20

When you half-fill a glass with mercury, the mercury curls down where it meets the glass. What can you conclude about the relative strengths of the inter atomic forces between the mercury atoms and the adhesive forces between the mercury atoms and the glass? (Caution: Mercury is toxic and should not be handled.)

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00:37

Problem 21

How does a gas differ from a plasma?

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00:56

Problem 22

What state of matter forms the Van Allen belts?

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01:08

Problem 23

Use the concept of pressure to explain why it is more comfortable to walk in bare feet across a paved driveway than across a gravel driveway.

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00:52

Problem 24

A closed book that is initially lying flat on a desk is turned to balance on its spine. Compare the forces exerted by the book on the table in the two orientations. Compare the pressures exerted by the book on the table in the two orientations.

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00:54

Problem 25

You place a small amount of water in a 1 -gallon can and bring it to a rapid boil. You take the can off the stove and screw the cap on tightly (the order is important here!). As the steam inside cools, it condenses back into water, causing the can to collapse. Why?

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00:49

Problem 26

At sea level each square inch of surface experiences a force of 14.7 pounds due to air pressure. You are carrying a cookie sheet loaded with chocolate chip cookies. The surface area of the cookie sheet is 250 square inches, which means that the downward force exerted by the air column above the cookie sheet is 3675 pounds! Why doesn't the cookie sheet feel this heavy?

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01:33

Problem 27

You repeat von Guericke's experiment (see Figure $12-7$ ) using somewhat smaller half spheres and find that two teams of eight horses are just strong enough to pull the half spheres apart. You then transport the apparatus to Denver, which is at an elevation of 1 mile. Will you need more or fewer horses to pull the half spheres apart? Why?

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01:20

Problem 28

A classmate explains that if your bathroom scale reads 150 pounds when you stand on it at sea level, it will read only 75 pounds on the top of an 18,000 -foot mountain, where atmospheric pressure is reduced by one-half. What is wrong with your classmate's reasoning? Would you expect the scale reading to be reduced at all as a result of the decrease in atmospheric pressure?

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00:32

Problem 29

On a weather map, you see areas of low pressure marked with an L and areas of high pressure marked with an H. By convention, the pressures reported are always corrected to the value they would have at sea level. If this were not the case, what letter would you see permanently above the mile-high city of Denver? Explain.

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01:05

Problem 30

Mountaineers often carry altimeters that measure altitude by measuring atmospheric pressure. If a low-pressure weather system moves in, will the altimeter report an altitude that is higher or lower than the true altitude? Explain.

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01:20

Problem 31

Are your ears going to hurt more because of water pressure if you are swimming 12 feet down in your swimming pool or 12 feet down in the middle of Lake Superior? Explain.

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00:50

Problem 32

How was it possible for the little Dutch boy to hold back the entire North Sea by putting his finger in the dike?

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01:13

Problem 33

Compare the pressures at the bottom of the two glasses shown in the following figure. Assume that both are filled to the same depth with the same fluid.
(picture cannot copy)

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01:25

Problem 34

Two identical wooden barrels are fitted with long pipes extending out their tops. The pipe on the first barrel is 1 foot in diameter, and the pipe on the second barrel is only $\frac{1}{2}$ inch in diameter. When the larger pipe is filled with water to a height of 20 feet, the barrel bursts. To burst the second barrel, will water have to be added to a height less than, equal to, or greater than 20 feet? Explain.

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01:07

Problem 35

Fresh water has a density of 1000 kilograms per cubic meter at $4^{\circ} \mathrm{C}$ and 998 kilograms per cubic meter at $20^{\circ} \mathrm{C}$ In which temperature water would you feel the greater pressure at a depth of 10 meters? Why?

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01:45

Problem 36

Salt water is more dense than fresh water. This means that the mass of 1 cubic centimeter of salt water is larger than that of 1 cubic centimeter of fresh water. Would a scuba diver have to go deeper in salt water or in fresh water to reach the same pressure? Why?

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01:10

Problem 37

Why can't water be "sucked" to a height greater than 10 meters even with a very good suction pump?

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00:51

Problem 38

At sea level even a perfect vacuum can raise water only 10 meters up a straw. At an elevation of 5000 feet in Bozeman, Montana, can water be raised to a height greater than, equal to, or less than 10 meters? Explain your reasoning.

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01:16

Problem 39

If you have a water well that is much deeper than about 5 meters, you put the pump at the bottom of the well and have it push the water up. Why is this better than placing the pump at the top?

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03:04

Problem 40

You place a long straw in a glass of water and find that, no matter how hard you suck, you cannot drink the water. You place the same straw in an unknown liquid $\mathrm{X}$ and find that you can drink. If you combine liquid $\mathrm{X}$ and water together in a glass, which one will float on the surface?

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00:31

Problem 41

Some toys contain two different-colored liquids that do not mix. If the purple liquid always sinks in the clear liquid as shown in the toy in the following figure, what can you say about the densities of the liquids?
(IMAGE CANNOT COPY)

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00:40

Problem 42

Spilled gasoline can sometimes be seen as a colorful film on the top of rain puddles. What does this tell you about the density of gasoline?

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00:49

Problem 43

Salt water is slightly more dense than fresh water. Will a boat float higher in salt water or fresh water?

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00:52

Problem 44

Use Archimedes' principle to explain why an empty freighter sits higher in the water than a loaded one.

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01:41

Problem 45

Salt water is slightly more dense than fresh water. Will a 50 -ton ship feel a greater buoyant force floating in a freshwater lake or in the ocean?

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01:22

Problem 46

Salt water is slightly more dense than fresh water. Will a 12-pound bowling ball feel a greater buoyant force sitting on the bottom of a freshwater lake or on the bottom of the ocean?

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01:57

Problem 47

When you blow air from your lungs, you are changing both your mass and your volume. Which of these effects explains why this causes you to sink to the bottom of a swimming pool?

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01:03

Problem 48

What happens to the depth of a scuba diver who takes a particularly deep breath?

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00:26

Problem 49

Use the data in Table $12-1$ to determine whether a block of lead would float in liquid mercury. What about a block of gold? (Caution: Do not try this experiment; mercury is very toxic!)

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00:43

Problem 50

Use the data in Table $12-1$ to determine which would float higher in liquid mercury, a block of copper or a block of silver.

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01:37

Problem 51

A submarine could be made to surface by either increasing the buoyant force or decreasing the weight. When a submarine's ballast tanks are blown out, which is happening?

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01:36

Problem 52

A scuba diver achieves neutral buoyancy by adjusting the volume of air in her air vest so that the buoyant force equals her weight. If she then kicks her feet and swims down an additional 20 feet, will the net force now be upward, zero, or downward? Explain.

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00:35

Problem 53

You have two cubes of the same size, one made of aluminum and the other of lead. Both cubes are allowed to sink to the bottom of a water-filled aquarium. Which cube, if either, experiences the greater buoyant force? Why?

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01:26

Problem 54

You have two cubes of the same size, one made of wood and the other of aluminum. Both cubes are placed in a water-filled aquarium. The wooden block floats, and the aluminum block sinks. Which cube, if either, experiences the greater buoyant force?

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01:36

Problem 55

An ice cube is floating in a glass of water. Will the water level in the glass rise, go down, or stay the same as the ice cube melts? Why?

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00:59

Problem 56

You are sitting in a boat in your swimming pool. There are six gold bricks in your boat. (You are rich!) If you throw the gold into the swimming pool, does the water level in the pool rise, fall, or stay the same? Explain.

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00:44

Problem 57

You place a dime flat on a tabletop a couple of inches from the edge. With your mouth near the edge of the table, you blow sharply across the top of the dime. Why does the dime pop up in the air? Try this.

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01:22

Problem 58

Why does your car get pulled sideways when a truck passes you going in the opposite direction on a two-lane highway?

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00:25

Problem 59

Why do table-tennis players put a lot of topspin on their shots?
(IMAGE CANNOT COPY)

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00:30

Problem 60

A partial vacuum can be created by installing a pipe at a right angle to a water faucet and turning on the water, as shown in the following figure. What is the physics behind this?
(IMAGE CANNOT COPY)

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02:04

Problem 61

The Green Building at the Massachusetts Institute of Technology (MIT) is a tall tower built on an inverted U-shaped base that is open to the Charles River Basin. Why might the doors in the opening have opened "by themselves" on windy days before revolving doors were installed to correct the design flaw?
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00:33

Problem 62

Why would an aneurysm (a widening of an artery) be especially subject to rupturing?

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00:27

Problem 63

What is the density of a substance that has a mass of $27 \mathrm{g}$ and a volume of $10 \mathrm{cm}^{3} ?$ Use Table $12-1$ to identify this substance.

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00:37

Problem 64

A small ball has a mass of $6.75 \mathrm{g}$ and a volume of $0.3 \mathrm{cm}^{3}$ Can you identify the material using Table $12-1 ?$

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00:36

Problem 65

A bowling trophy has a mass of $180 \mathrm{g}$. When placed in water, the trophy displaces $600 \mathrm{cm}^{3}$. What is the average density of the trophy?

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01:02

Problem 66

If Archimedes' crown had a mass of $1 \mathrm{kg}$ and a volume of $120 \mathrm{cm}^{3},$ was the crown made of pure gold? Explain.

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00:41

Problem 67

A solid ball with a volume of $0.4 \mathrm{m}^{3}$ is made of a material with a density of $3000 \mathrm{kg} / \mathrm{m}^{3} .$ What is the mass of the ball?

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00:44

Problem 68

What is the mass of a lead sinker with a volume of $3 \mathrm{cm}^{3} ?$

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01:41

Problem 69

Given that most people are just about neutrally buoyant, it is reasonable to estimate the density of the human body to be about that of water. Use this assumption to find the volume of a $70-\mathrm{kg}$ person.

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00:50

Problem 70

A cube with a mass of $48 \mathrm{g}$ is made from a metal with a density of $6 \mathrm{g} / \mathrm{cm}^{3} .$ What is the volume of the cube and the length of each edge?

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01:45

Problem 71

If $1000 \mathrm{cm}^{3}$ of a gas with a density of $0.0009 \mathrm{g} / \mathrm{cm}^{3} \mathrm{con}-$ denses to a liquid with a density of $0.9 \mathrm{g} / \mathrm{cm}^{3},$ what is the volume of the liquid?

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01:27

Problem 72

A cube of ice, $10 \mathrm{cm}$ on each side, is melted into a measuring cup. What is the volume of the liquid water?

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01:45

Problem 73

Calculate the weight of a column of fresh water with cross sectional area $1 \mathrm{m}^{2}$ and height $10 \mathrm{m}$. What pressure does this create at the bottom of the column of water? How does this compare to atmospheric pressure?

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01:52

Problem 74

Calculate the height of a column of mercury with cross sectional area $1 \mathrm{m}^{2}$ such that it has the same weight as the column of water in Exercise 73

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01:32

Problem 75

Given that atmospheric pressure drops by a factor of 2 for every gain in elevation of $18,000 \mathrm{ft}$, what is the height of a mercury column in a barometer located in an unpressurized compartment of an airliner flying at $36,000 \mathrm{ft}^{2}.$

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01:35

Problem 76

Two barometers are made with water and mercury. If the mercury column is 30 in. tall, how tall is the water column?

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01:15

Problem 77

Each cubic inch of mercury has a weight of 0.5 lb. What is the pressure at the bottom of a column of mercury 30 in. tall if there is a vacuum above the mercury?

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02:08

Problem 78

If $1 \mathrm{m}^{3}$ of water has a mass of $1000 \mathrm{kg},$ what is the pressure at a depth of $150 \mathrm{m} ?$ Is the atmospheric pressure important?

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00:45

Problem 79

An object has a mass of $150 \mathrm{kg}$ and a volume of $0.2 \mathrm{m}^{3}$ What is its average density? Will this object sink or float in water?

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00:51

Problem 80

Will an object with a mass of $1000 \mathrm{kg}$ and a volume of $1.6 \mathrm{m}^{3}$ float?

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01:08

Problem 81

A $500-\mathrm{g}$ wooden block is lowered carefully into a completely full beaker of water and floats. What is the weight of the water, in newtons, that spills out of the beaker?

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01:04

Problem 82

A $400-\mathrm{cm}^{3}$ block of aluminum $\left(D=2.7 \mathrm{g} / \mathrm{cm}^{3}\right)$ is lowered carefully into a completely full beaker of water. What is the weight of the water, in newtons, that spills out of the beaker?

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04:10

Problem 83

A ball of wax is lowered carefully into a completely full beaker of water, where it floats. This causes $18 \mathrm{cm}^{3}$ of water to spill out. The same ball of wax is then lowered carefully into a completely full beaker of ethyl alcohol $\left(D=0.79 \mathrm{g} / \mathrm{cm}^{3}\right),$ where it sinks, causing $20 \mathrm{cm}^{3}$ of alcohol to spill out. Which of these two experiments allows you to find the wax's mass, and which allows you to find its volume? Find the density of the wax.

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03:00

Problem 84

A yellow object is lowered carefully into a completely full beaker of water, where it floats. This causes $28 \mathrm{cm}^{3}$ of water to spill out. The same object is then lowered carefully into a completely full beaker of gasoline $(D=0.68$ $\left.\mathrm{g} / \mathrm{cm}^{3}\right),$ where it sinks, causing $40 \mathrm{cm}^{3}$ of gasoline to spill out. In which liquid does the yellow object experience the greater buoyant force?

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02:39

Problem 85

A cubic meter of copper has a mass of 8930 kg. The block of copper is lowered into a lake by a strong cable until the block is completely submerged. Draw a free-body diagram for the block. Find the buoyant force on the block and the tension in the cable.

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02:30

Problem 86

A ball fully submerged in a bathtub has a volume of $5 \mathrm{cm}^{3}$ and a mass of $30 \mathrm{g}$. Draw a free-body diagram for the ball. What is the normal force of the tub on the ball?

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