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All Textbook Solutions for Conceptual Physics: The High School Physics Program
5AWhich usually contains more water vapor—warm air or cool air?Why does warm moist air form clouds when it rises?8AWhy do you feel less chilly if you dry yourself inside the shower stall after taking a shower?10AWhy does the temperature at which a liquid boils depend on atmospheric pressure?Why is a pressure cooker even more useful when cooking food in the mountains than when cooking at sea level?13AHow can water be made to both boil and freeze at the same time?15A16A17AWhat is the effect of rapid evaporation on the temperature of water?In a refrigerator, does the food cool when a vapor turns to a liquid, or vice versa?Why is it important that a finger be wet before it is touched to a hot clothes iron?Calculate the energy absorbed by 20 grams of water that warms from 30C to 90C.Calculate the energy needed to melt 50 grams of 0C ice.Calculate the energy needed to melt 100 grams of 0C ice and then heat it to 30C.Calculate the energy absorbed by 20 grams of 100C water that is turned into 100C steam.Calculate the energy released by 20 grams of 100C steam that condenses to 100C water.Calculate the total energy released when 20 grams of steam condenses to water, cools, and then turns to ice at 0C.27A28AClassmate Matthew says that if all the molecules in a particular liquid had the same speed, and some were able to evaporate, the remaining liquid would not undergo cooling. Do you agree or disagree, and what is your explanation?You can determine wind direction if you wet your finger and hold it up into the air. Explain.Give two reasons why pouring a hot cup of coffee into a saucer results in faster cooling.At a picnic, why would wrapping a bottle in a wet cloth be a better method of cooling than placing the bottle in a bucket of cold water?Why does dew form on the surface of a cold soft-drink can?Air-conditioning units contain no water whatever, yet it is common to see water dripping from them when they're running on a hot day. Explain.35A36AIf a large tub of water is kept in a small unheated room, even on a very cold day the temperature of the room will not go below 0C. Why not?On a clear night, why does more dew form in an open field than under a tree or beneath a park bench?Machines used for making snow at ski areas blow a mixture of compressed air and water through a nozzle. The temperature of the mixture may initially be well above the freezing temperature of water, yet crystals of snow are formed as the mixture is ejected from the nozzle. Explain how this happens.People who live where snowfall is common will attest to the fact that air temperatures are generally higher on snowy days than on clear days. Some people get cause and effect mixed up when they say that snowfall cannot occur on very cold days.41AWhy is it that, in cold winters, a tub of water placed in a farmers canning cellar helps prevent canned food from freezing?Why will spraying fruit trees with water before a frost help to protect the fruit from freezing?Andrew says that potatoes will cook faster in vigorously boiling water than in gently boiling water. Madison disagrees. Whom do you agree with, and why?Why is the constant temperature of boiling water on a hot stove evidence that boiling is a cooling process? (What would happen to its temperature if boiling were not a cooling process?)46AElizabeth says that the boiling temperature of water decreases when the water is under reduced pressure. Austin says the opposite is true—that reduced pressure increases the boiling point. Whom do you agree with and why?Nick suspends a small jar of water in a saucepan, careful that the bottom of the jar doesnt rest on the bottom of the saucepan. Nick then puts water in the pan, surrounding the jar. He puts the saucepan on a hot stove and is puzzled to see that although the water in the pan comes to a boil, the water in the jar doesnt. He looks to you for an explanation. Explain.Room-temperature water will boil spontaneously in a vacuum—on the moon, for example. Could you cook an egg in this boiling water? Defend your answer.Your inventor friend proposes a design for cookware that will allow boiling to take place at a temperature of less than 100C so that food can be cooked with the consumption of less energy. Comment on this idea.Hydrothermal vents are openings in the ocean floor that discharge very hot water. Water emerging at nearly 280C from one such vent off the Oregon coast, some 2400 m beneath the surface, is not boiling. Provide an explanation.In the power plant of a nuclear submarine, the temperature of the water in the reactor is above 100C. How is this possible?53AHow much steam at 100C must be condensed in order to melt 1 gram of 0C ice and have the resulting ice water remain at 0C? (The answer is not 0.148 grams!)How many calories ate given off by 1 gram of 100C steam that changes phase to 1 gram of ice at 0C?If 20 grams of hot water at 80C is poured into a cavity in a very large block of ice at 0C, what will be the final temperature of the water in the cavity? How much ice must melt in order to cool the hot water down to this temperature?Answer Questions 57—61 in terms of joules rather than calories. How much energy is needed to melt 5 kg of ice at 0C?Answer Questions 57—61 in terms of joules rather than calories. How much energy is given to your body when 0.5 kg of steam condenses on your skin?Answer Questions 57—61 in terms of joules rather than calories. If that same amount of energy (answer to question 58) were used to warm 4 kg of water (8 times as much!) initially at 0C, what would be the final temperature of the water?60AAnswer Questions 57—61 in terms of joules rather than calories. How much energy is needed to change 1 kg of ice at 10C to steam at 120C?What is the meaning of the Greek words from which we get the word thermo-dynamics?Is the study of thermodynamics concerned primarily with microscopic or macroscopic processes?What is the lowest possible temperature on the Celsius scale? On the Kelvin scale?What is the temperature of melting ice in kelvins? Of boiling water?How does the law of the conservation of energy relate to the first law of thermodynamics?What happens to the internal energy of a system when work is done on it? What happens to its temperature?7A8A9AWhat happens to the temperature of air when it is adiabatically compressed? When it adiabatically expands?What generally happens to the temperature of rising air?What generally happens to the temperature of sinking air?How does the second law of thermodynamics relate to the direction of heat flow?What three processes occur in every heat engine?What is thermal pollution?If all friction could be removed from a heat engine, would it be 100% efficient? Explain.What is the ideal efficiency of a heat engine that operates with its hot reservoir at 500 K and its sink at 300 K?Why are heat engines intentionally run at high operating temperatures?Give at least two examples to distinguish between organized energy and disorganized energy.How much of the electrical energy transformed by a common lightbulb becomes heat energy?With respect to orderly and disorderly states, what do natural systems tend to do? Can a disorderly state ever transform to an orderly state? Explain.What is the physicists term for a measure of messiness?Under what condition can entropy decrease in a system?What is the relationship between the second law of thermodynamics and entropy?25ACalculate the ideal efficiency of a heat engine that takes in energy at 800 K and expels heat to a reservoir at 300 K.Calculate the ideal efficiency of a ships boiler when steam comes out at 530 K, pushes through a steam turbine, and exits into a condenser that is kept at 290 K by circulating seawater.Calculate the ideal efficiency of a steam turbine that has a hot reservoir of 112C high-pressure steam and a sink at 27C.In a heat engine driven by ocean temperature differences, the heat source (water near the surface) is at 293 K and the heat sink (deeper water) is at 283 K. Calculate the ideal efficiency of the engine.On which temperature scale does the average kinetic energy of molecules double when the temperature doubles?31A32AMaria vigorously shakes a can of liquid back and forth for more than a minute. Does the temperature of the liquid increase? Why or why not? (Try it and see.)When you pump a tire with a bicycle pump, the cylinder of the pump becomes hot. Give two reasons why this is so.What happens to the gas pressure within a sealed gallon can when it is heated? When it is cooled?We know that warm air rises. So it might seem that the air temperature should be higher at the top of mountains than down below. But the opposite is most often the case. Why?The combined molecular kinetic energies of molecules in a very large container of cold water are greater than the combined molecular kinetic energies in a cup of hot tea. Pretend you partially immerse the teacup in the cold water and that the tea absorbs 10 joules of energy from the water and becomes hotter, while the water that gives up 10 joules of energy becomes cooler. Would this energy transfer violate the first law of thermodynamics? The second law of thermodynamics? Explain.38A39AWill the efficiency of a car engine increase, decrease; or remain the same if the muffler is removed? If the car is driven on a very cold day? Defend your answers.Consider the inverted soft drink can placed in a pan of water, as featured in the Discover! box in Section 24.5. The can is crushed by atmospheric pressure. Would crushing occur if the water were hot but not boiling? Would it be crushed in boiling water? (Try it and see!)A mixture of fuel and air is burned rapidly in a combustion engine to push a piston in the engine that m turn propels the vehicle. In a jet engine, a mixture of fuel and air is burned rapidly and, instead of pushing pistons, pushes the aircraft itself. Which do you suppose is more efficient?In buildings that are being heated electrically, is it wasteful to turn on all the lights? Is turning on all the lights wasteful if the building is being cooled by air conditioning? Defend your answers.Why is thermal pollution' a relative term?Is it possible to construct a heat engine that produces no thermal pollution? Defend your answer.What happens to the efficiency of a heat engine when the temperature of the reservoir into which heat energy is ejected is lowered?Water put into a freezer compartment in your refrigerator goes to a state of less molecular disorder when it freezes. Is this an exception to the entropy principle? Explain.Carlos says that perpetual motion machines are impossible to construct. John says that perpetual motion is common in nature—the motion of molecules, for example. Do you agree with Carlos, John, or both?Helium has the special property that its internal energy is directly proportional to its absolute temperature. Consider a flask of helium with a temperature of 10C. If it is heated until it has twice the internal energy, what will its temperature be?Imagine a giant dry-cleaners bag full of air at a temperature of 35C floating like a balloon with a string hanging from it 10 km above the ground. Estimate its temperature if you were able to yank it suddenly to Earths surface.What is the ideal efficiency of an automobile engine wherein fuel is heated to 2700 K and the outdoor air is 300 K?52AWhich heat engine has greater ideal efficiency, one that operates between the temperature 600 K and 400 K or one that operates between 500 K and 400 K? Explain how your answer conforms to the idea that a higher operating temperature yields higher efficiency.To increase the efficiency of a heat engine, would it be better to increase the temperature of the reservoir while holding the temperature of the sink constant, or to decrease the temperature of the sink while holding the temperature of the reservoir constant? Show your work.A heat engine takes in 100 kJ of energy from a source at 800 K and expels 50 kJ to a reservoir at 300 K. Calculate the ideal efficiency and the actual efficiency of the engine.A certain heat engine takes in 25 kJ of heat and exhausts 17 kJ. Chris says that the efficiency of the engine is 0.32. Confirm his findings.During one cycle, an ideal heat engine exhausts 3800 J of heat while performing 1200 J of useful work. Anthony says the efficiency of the engine is 0.24. Show that he is correct.A heat engine operates between Thot=750C and Tcold=35C. Michael says that the theoretical maximum efficiency is about 70%. Do you agree? If so, show why. If not, show why not.59ADoes a vibration or a wave spread out through space?What is the period of a pendulum that takes one second to make a complete back-and-forth vibration?Suppose that a pendulum has a period of 1.5 seconds. How long does it take to make a complete back-and-forth vibration?Is a pendulum with a 1.5-second period longer or shorter in length than a pendulum with a 1-second period?How is a sine curve related to a wave?Distinguish among these different parts of a wave: amplitude, crest, trough, and wavelength.Distinguish between the period and the frequency of a vibration or a wave. How do they relate to one another?Does the medium in which a wave travels move along with the wave itself? Defend your answer.How does the speed of a wave relate to its wavelength and frequency?As the frequency of sound is increased, does the wavelength increase or decrease? Give an example.Distinguish between a transverse wave and a longitudinal wave.Distinguish between constructive interference and destructive interference.Is interference a property of only some types of waves or of all types of waves?What causes a standing wave?When a wave source moves toward a receiver, does the receiver encounter an increase in wave frequency, wave speed, or both?Does the Doppler effect occur for only some types of waves or all types of waves?Compared with the speed of water waves how fast must a bug swim to keep up with the waves it produces? How fast must a boat move to produce a bow wave?Distinguish a bow wave from a shock wave.19AIf you encounter a sonic boom, is that evidence that an aircraft just exceeded the speed of sound to become supersonic?A fire engines siren emits a certain frequency. Rank from greatest to least the apparent frequency heard by the stationary listener in each scenario. (A) The fire engine is traveling toward a listener at 30 m/s. (B) The fire engine is traveling away from a listener at 5 m/s. (C) The fire engine is traveling toward a listener at 5 m/s. (D) The fire engine is traveling away from a listener at 30 m/s.Shown below are four different pairs of transverse wave pukes that move toward each other. At some point in time the pulses meet and interact (interfere) with each other. Rank the four cases from greatest to least on the basis of the height of the peak that results when the centers of the pairs coincide.All the waves below have the same speed in the same medium. Use a ruler and rank these waves from greatest to least according to amplitude, wavelength, frequency, and period.The four sets of waves below are a top view of circular wave patterns made by a bug jiggling on the surface of water. Rank them from greatest to least based on the speed of the bug.The shock waves depicted below are produced by supersonic aircraft. Rank them from greatest to least based on the speed of the aircraft.A nurse counts 76 heartbeats in one minute. What are the period and frequency of the hearts oscillations?New Yorks 300-m high Citicorp® Tower oscillates in the wind with a period of 6.80 Calculate its frequency of vibration.Calculate the speed of waves in a puddle that are 0.15 m apart and made by tapping the water surface twice each second.Calculate the speed of waves in water that are 0.4 m apart and have a frequency of 2 Hz.30ADoes the period of a pendulum depend of the mass of the bob? On the length of the string?If a pendulum is shortened, does the frequency increase or decrease? What about its period?Carmelita swings to and fro in a sitting position on a playground swing. William says that if she stands while swinging, a longer time will occur between back-and-forth swings. Carlos says no, that the to-and-fro time of the swing will be unaffected. Who, if either, do you agree with?You dip your finger repeatedly into a puddle of water and make waves. What happens to the wavelength if you dip your finger more frequently?If you double the frequency of a vibrating object, what happens to its period?How does the frequency of vibration of a small object floating in water compare to the number of waves passing it each second?If you triple the frequency of a vibrating object, what will happen to its period?Red light has a longer wavelength than violet light. Which has the greater frequency?How far, in terms of wavelength, does a wave travel in one period?If a wave vibrates up and down twice each second and travels a distance of 20 m each second, what is its frequency? Its wave speed? (Why is this question best answered by careful reading of the question rather than searching for a formula?)The wave patterns seen in Figure 25.6 are composed of circles. What does this tell you about the speed of the waves in different directions?Sound from Source A has a frequency twice as great as the frequency of sound from Source B. Compare the wavelengths of sound from the two sources.What kind of motion should you impart to a stretched coiled spring to produce a transverse wave? A longitudinal wave?Would it be correct to say that the Doppler effect is the apparent change in the speed of a wave due to the motion of the source? (Why is this question a test of reading comprehension as well as a test of physics?)In the Doppler effect, does frequency change? Does wavelength change? Does wave speed change?Can the Doppler effect be observed with longitudinal waves, with transverse waves, or with both?47AWhen a driver blows his horn while approaching a stationary listener, the listener hears an increase in the frequency of the horn. Would the listener hear an increase in the frequency of the horn if she were also in a car traveling at the same speed in the same direction as the first driver? Explain.Astronomers find that light coming from point A at the edge of the sun has a slightly higher frequency than light from point B at the opposite side. What do these measurements tell us about the suns motion?Does a boat moving through the water always produce a bow wave? Defend your answer.Whenever you watch a high-flying aircraft overhead, it seems that its sound comes from behind the craft rather than from where you see it. Why is this?How does the angle of the V shape of a bow wave depend on the speed of the wave source?Why is it that a subsonic aircraft, no matter how loud it may be, cannot produce a sonic boom?True or false: A sonic boom occurs only when an aircraft is breaking through the sound barrier. Defend your answer.55AThe period of a simple pendulum is given by T=2Lg, where g is the acceleration of gravity and L is the length of the pendulum. In a lab, you want to double the period of a certain pendulum. Your friend says you'll have to make the pendulum twice as long. Do you agree with your friend?Maria shows her friends a simple 31 -cm-long pendulum. Her teacher, looking on, asks if she can predict the period of the pendulum before she demonstrates it. Whats your prediction?The Foucault pendulum in the rotunda of the Griffith Observatory in Los Angeles has a 110-kg brass ball at the end of a 12.2-m-long cable. What is the period of this pendulum?You are looking through your grandparents' window and notice a hummingbird feeder hanging by a rope. You cant see the top of the rope, but you notice that in a gentle breeze the feeder moves back and forth with a period of 4.0 seconds. You make a calculation and announce to your grandparents that the rope is 4 m long. Your grandparents go outside and measure the rope. Should they be impressed with you?For your science fair project you decide to make a simple pendulum for a grandfather clock, such that the period of the pendulum is 2.00 seconds. Show that the length of your pendulum should be just slightly less than the length of a meterstick. (Use g=9.8m/s2 here.)61AA design engineer figures that a proposed new skyscraper will swing to and fro in strong winds at a frequency of 0.15 Hz. A new assistant asks how much time a person in the skyscraper will experience during each complete swing. Whats your answer?In lab you strike a tuning fork that has a frequency of 340 Hz. For a speed of sound of 340 m/s, how does the wavelength of the resulting sound wave compare with the length of a meter stick?If a wave vibrates back and forth three times each second, and its wavelength is 2 meters, what is its frequency? Its period? Its speed?While watching ocean waves at the dock of the bay, Otis notices that 10 waves pass beneath him in 30 seconds. He also notices that the crests of successive waves exactly coincide with the posts that are 5 meters apart. What are the period, frequency, wavelength, and speed of the ocean waves?The crests on a long surface water wave are 20 m apart, and in 1 minute 10 crests pass by. What is the speed of this wave?Radio waves are electromagnetic waves that travel at the speed of light, 300,000 kilometers per second. What is the wavelength of FM radio waves received at 100 megahertz on your radio dial?The wavelength of red light is about 700 nanometers, or 7107m. The frequency of the red light reflected from a metal surface and the frequency of the vibrating electron that produces it are the same. What is this frequency?The half-angle of the shock-wave cone generated by a supersonic aircraft is 45. What is the speed of the plane relative to the speed of sound?Tie a rubber tube, a spring, or a rope to a fixed support and produce standing waves, as Figure 25.14 suggests. How many nodes can you produce? How can you change the number of nodes?What is the source of all sounds?How does pitch relate to frequency?What is the average frequency range of a young persons hearing?Distinguish between infrasonic and ultrasonic sound.a. Distinguish between compressions and rarefactions of a sound wave. b. How are compressions and rarefactions produced?Light can travel through a vacuum, as is evidenced when you see the sun or the moon. Can sound travel through a vacuum also? Explain why or why not.7AHow does the speed of sound in air compare with its speed in water and in steel?Why does sound travel faster in solids and liquids than in gases?Is sound intensity subjective or is loudness subjective? Why?Why do different objects make different sounds when dropped on a floor?What does it mean to say that everything has a natural frequency of vibration?Why is sound louder when a vibrating source is held to a sounding board?What is the relationship between forced vibration and resonance?Why can a tuning fork or bell be set into resonance, while tissue paper cannot?How is resonance produced in a vibrating object?What does tuning in a radio station have to do with resonance?Is it possible for one sound wave to cancel another? Explain.Why does destructive interference occur when the path lengths from two identical sources differ by half a wavelength?How does interference of sound relate to beats?What is the beat frequency when a 494-Hz tuning fork and a 496-Hz tuning fork are sounded together?The three waves below have the same frequency and travel in different media. Rank their speeds from greatest to least,A pair of tuning forks of frequencies f1 and f2 are sounded together. Rank from greatest to least the beat frequencies produced by the following pairs of tuning forks. (A) f1=650Hz;f2=654Hz (B) f1=300Hz;f2=305Hz (C) f1=200Hz;f2=208Hz (D) f1=800Hz;f2=801HzIf the moon blew up, why wouldnt we be able to hear it?When watching at a baseball game, we often hear the bat hitting the ball after we actually see the hit. Why?In the stands of a racetrack, you notice smoke from the starters gun before you hear it fire. Explain.In an Olympic competition, a microphone picks tip the sound of the starters gun and sends it electrically to speakers at every runners starting block. Why?Why will marchers at the end of a long parade following a band be out of step with marchers nearer the band?You watch a distant farmer driving a stake into the ground with a sledgehammer. He hits the stake at a regular rate of one stroke per second. You hear the sound of the blows exactly synchronized with the blows you see. And then you hear one more blow after you see him stop hammering. How far away is the farmer?When a sound wave propagates past a point in the air, what are the changes that occur in the pressure of air at this point?If the speed of sound depended on its frequency, would you enjoy a concert sitting in the second balcony?If the frequency of sound is doubled, what change will occur in its speed? What change will occur in its wavelength?Why is an echo weaker than the original sound?How much more intense is a close whisper than a sound at the threshold of hearing?The signal-to-noise ratio for a tape recorder is listed at 50 dB, meaning that when music is played back, the intensity level of the music is 50 dB greater than that of the noise from tape hiss and so forth. By what factor is the sound intensity of the music greater than that of the noise?If the handle of a tuning fork is held solidly against a table, the sound becomes louder. Why? How will this affect the length of the time the fork keeps vibrating? Explain, using the law of energy conservation.The sitar, an Indian musical instrument, has a set of strings that vibrate and produce music, even though they are never plucked by the player. These sympathetic strings' are identical to the plucked strings and are mounted below them. What is your explanation?Suppose a piano tuner hears 2 beats per second when listening to the combined sound from her tuning fork and the piano note being tuned. After slightly tightening the string, she hears I beat per second. Should she loosen or should she further tighten the string?Why is it dangerous for people in the balcony of an auditorium to stamp their feet in a steady rhythm?Why is the sound of a harp soft in comparison with the sound of a piano?What physics principle is used by Laura when she pumps in rhythm with the natural frequency of the swing?Suppose a sound wave and an electromagnetic wave have the same frequency. Which has the longer wavelength?A special device transmits out-of-phase sound to a jackhammer operator through earphones. Over the noise of the jackhammer, the operator can easily hear your voice while you are unable to hear his. Explain.44AA bat flying in a cave emits a sound and receives its echo 0.10 s later. Show that the distance to the wall of the cave is 17 m.An oceanic depth-sounding vessel surveys the ocean bottom with ultrasonic sound that travels 1530 m/s in seawater. Find the depth of the water if the time delay of the echo to the ocean floor and back is 8 seconds.On a field trip to Echo Cave, you clap your hands and receive an echo 1 second later. How far away is the cave wall?Susie hammers on a block of wood when she is 85 m from a large brick wall. Each time she hits the block, she hears an echo 0.5 s later. With this information, show that the speed of sound is 340 m/s.49ASuppose your friend is foolish enough to play his keyboard instrument underwater, where the speed of sound is 1,500 m/s. a. Show that the wavelength of the middle-C tone in water would be 5.86 m. b. Explain why middle C (or any other tone) has a longer wavelength in water than in air.Two sounds, one at 240 Hz and the other at 243 Hz, occur at the same time. What beat frequency do you hear?Two notes are sounding, one of which is 440 Hz. If a beat frequency of 5 Hz is heard, what is the other notes frequency?What beat frequencies are possible with tuning forks of frequencies 256, 259, and 261 Hz?55ABlow over the tops of two identical empty bottles and see if the tone produced is of the same pitch. Then put one in a freezer and try the procedure again. Sound will travel more slowly in the colder denser air of the cold bottle and the note will be lower. Try it and see.1AHow long does it take for light to travel across the diameter of Earths orbit around the sun?How did a spinning octagonal mirror help Michelson calculate the time that light took to make the round trip to the distant mountain?How long does light take to travel from the sun to Earth? From the star Alpha Centauri to Earth?How long does light take to travel a distance of one light-year?What is the source of electromagnetic waves?7AHow do the frequencies of infrared and ultraviolet light compare?How does the role of inertia relate to the rate at which electric charges can be forced into vibration?Different bells and tuning forks have their own natural vibrations and emit their own tones when struck. How is this analogous to atoms, molecules, and light?11AWill glass be transparent to light with frequencies that match its own natural frequencies?Does the time delay between the absorption and reemission of light affect the average speed of light in a material? Explain.When light encounters a material, it can build up vibrations in the electrons of certain atoms that may be intense enough to last over a long period of time. Will the energy of these vibrations tend to be absorbed and turned into heat or absorbed and reemitted as light?15AWhat happens to the energy of light when it encounters an opaque material?17ADistinguish between an umbra and a penumbra.a. Distinguish between a solar eclipse and a lunar eclipse. b. Which type of eclipse is dangerous to your eyes if viewed directly?What is the difference between light that is polarized and light that is not?Why is light from a common lamp or from a candle flame nonpolarized?In what direction is the polarization of the glare that reflects from a horizontal surface?How do polarizing filters allow each eye to see separate images in the projection of three-dimensional slides or movies?When you look at a distant galaxy through a telescope, how is it that you're looking backward in time?25A26A27A28A29AYour friend says that any radio wave travels appreciably faster than any sound wave. Do you agree or disagree, and why?Are the wavelengths of radio and television signals longer or shorter than waves detectable by the human eye?32A33AIf the mirror in Michelsons apparatus had had six sides instead of eight, would it have had to spin faster or more slowly to measure the speed of light? Explain.If a one-side-silvered plane mirror were used in the Michelson apparatus, how much faster would it have had to spin so reflected light would be seen in the telescope?36AShort wavelengths of visible light interact more frequently with the atoms in glass than do longer wavelengths. Does this interaction time tend to speed up or slow down the average speed of short-wavelength light in glass?Imagine that a person can walk only at a certain pace—no faster and no slower. If you time her uninterrupted walk across a room of known length, you can calculate her walking speed. If, however, she stops momentarily along the way to greet others in the room, the extra time spent in her brief interactions gives an average speed across the room that is less than her walking speed. How is this like light passing through glass? How is it different?If you fire a ball through a pile of sand, it will slow down in the sand and emerge at less than its initial speed. But when light shines on a pane of glass, even though it slows down inside, its speed upon emerging is the same as its initial speed. Explain.Short wavelengths of visible light interact more frequently with the atoms in glass than do longer wavelengths. Which do you suppose takes the longer time to get through glass—red light or blue light?Suppose that sunlight is incident upon both a pair of reading glasses and a pair of sunglasses. Which pair would you expect to be warmer, and why?42AThe intensity of light decreases as the inverse square of the distance from the source. Does this mean that light energy is lost? Explain.Only some of the people on the daytime side of Earth can witness a solar eclipse when it occurs, whereas all the people on the nighttime side of Earth can witness a lunar eclipse when it occurs. Why is this so?Lunar eclipses are always eclipses of a full moon. That is, the moon is always seen full just before and after Earths shadow passes over it. Why can we never have a lunar eclipse when the moon is in its crescent or half-moon phase?Why do Polaroid sunglasses reduce glare, whereas unpolarized sunglasses simply cut down on the total amount of light reaching our eyes?An ideal polarizing filter transmits 50% of the incident nonpolarized light. Why is this so?What percentage of light would be transmitted by two ideal polarizing filters, one atop the other, with their axes aligned? With their axes crossed at right angles?Light with wavelength and frequency f in air slows to a speed v when transmitted through a piece of plastic. a. What is the lights frequency in the plastic? b. What is the lights wavelength in the plastic?50AAbout 150 years ago Armand Fizeau used a toothed wheel to measure the speed of light. One particular wheel had 150 teeth with 150 spaces (gaps) between them—the teeth and the gaps were of equal width. Light travels through the gap and is reflected back along its path by mirror 8 km away. At what speed must the wheel rotate in order for the light to arrive back at the wheel and pass through the gap next to the one through which it first passed?52A53A54AThe nearest star beyond the sun is Alpha Centauri, which is 4.21016 meters away. If we were to receive a radio message from this star today, show that it would have been sent 4.4 years ago.The Hydra galaxy is moving away from Earth at 6.0107m/s. What fraction of the speed of light is this?When listening to a radio station broadcasting at 101 MHz (101 million wave vibrations per second), you wonder how long the wavelength of these waves is. What is the answer, and how does it compare to your height?Blue-green light has a frequency of about 61014Hz. a. Using the relationship c=f, show that its wavelength in air is 5107m. b. How much larger is this wavelength than the diameter of an atom, which is about 1010m?Some laser pointers emit light waves with a wavelength of 533 nm. a. What is the frequency of this light? b. Find the color of this light.