Q&A Hero

Q: The Stanford linear accelerator contains hundreds of brass disks tightly fitted into a steel tube (see figure). The coefficient of linear expansion of the brass is 2.00 x10-5per C°. The system was assembled by cooling the disks in dry ice (-57°C) to enable them to just slide into the close-fitting tube. If the diameter of a disk is 80.00 mm at 43°C, what is its diameter in the dry ice?A) 78.400 mmB) 79.998 mmC) 80.160 mmD) 79.840 mmE) none of these

Q: A surveyor's 30-m steel tape is correct at 68ï‚°F. On a hot day the tape has expanded to 30.02 m. On that day, the tape indicates a distance of 15.52 m between two points. The true distance between these points is: A) 15.50 m B) 15.51 m C) 15.52 m D) 15.53 m E) 15.54 m

Q: Thin strips of iron and zinc are riveted together to form a bimetallic strip which bends when heated. The iron is on the inside of the bend because: A) it has a higher coefficient of linear expansion B) it has a lower coefficient of linear expansion C) it has a higher specific heat D) it has a lower specific heat E) it conducts heat better

Q: The two metallic strips that constitute some thermostats must differ in: A) length B) thickness C) mass D) rate at which they conduct heat E) coefficient of linear expansion

Q: Possible units for the coefficient of volume expansion are:A) mm/C°B) mm3/C°C) (C°)3D) 1/(C°)3E) 1/C°

Q: It is more difficult to measure the coefficient of volume expansion of a liquid than that of a solid because: A) no relation exists between linear and volume expansion coefficients B) a liquid tends to evaporate C) a liquid expands too much when heated D) a liquid expands too little when heated E) the containing vessel also expands

Q: One degree is the same on the following temperature scales: A) Fahrenheit and Celsius B) Fahrenheit and Kelvin C) Celsius and Kelvin D) Fahrenheit and Absolute E) none of the above

Q: The air temperature on a summer day might be about:A) 0°CB) 10°CC) 25°CD) 80°CE) 125°C

Q: A thermometer indicates 98.6°C. It may be:A) outdoors on a cold dayB) in a comfortable roomC) in a cup of hot teaD) in a normal person's mouthE) in liquid air

Q: Room temperature is about 20 degrees on the: A) Kelvin scale B) Celsius scale C) Fahrenheit scale D) absolute scale E) C major scale

Q: A Kelvin thermometer and a Fahrenheit thermometer both give the same reading for a certain sample. The corresponding Celsius temperature is:A) 574°CB) 232°CC) 301°CD) 614°CE) 276°C

Q: Which one of the following statements is true?A) temperatures differing by 25°on the Fahrenheit scale must differ by 45°on the Celsius scaleB) 40 K corresponds to -40°CC) temperatures which differ by 10°on the Celsius scale must differ by 18°on the Fahrenheit scaleD) water at 90°C is warmer than water at 202°FE) 0°F corresponds to -32°C

Q: Fahrenheit and Kelvin scales agree numerically at a reading of:A) -40B) 0C) 273D) 301E) 574

Q: There is a temperature at which the reading on the Kelvin scale is numerically: A) equal to that on the Celsius scale B) lower than that on the Celsius scale C) equal to that on the Fahrenheit scale D) less than zero E) none of the above

Q: The diagram shows four thermometers, labeled W, X, Y, and Z. The freezing and boiling points of water are indicated. Rank the thermometers according to the size of a degree on their scales, smallest to largest. A) W, X, Y, Z B) Y, W, X, Z C) Z, Y, W, X D) Z, X, W, Y E) W, Y, Z, X

Q: When a certain constant volume gas thermometer is in thermal contact with water at its triple point (273.16 K) the pressure is 6.30x104Pa. For this thermometer a kelvin corresponds to a change in pressure of about:A) 4.34x102PaB) 2.31x102PaC) 1.72x103PaD) 2.31x103PaE) 1.72 x107Pa

Q: A constant-volume gas thermometer is used to measure the temperature of an object. When the thermometer is in contact with water at its triple point (273 K) the pressure in the thermometer is 8.50x104Pa. When it is in contact with the object the pressure is 9.65x104Pa. The temperature of the object is:A) 41.0 KB) 114 KC) 241 KD) 310 KE) 314 K

Q: Constant-volume gas thermometers using different gases all indicate nearly the same temperature when in contact with the same object if: A) the volumes are all extremely large B) the volumes are all the same C) the pressures are all extremely large D) the pressures are the same E) the particle concentrations are all extremely small

Q: The "triple point" of a substance is that point for which the temperature and pressure are such that: A) only solid and liquid are in equilibrium B) only liquid and vapor are in equilibrium C) only solid and vapor are in equilibrium D) solid, liquid and vapor are all in equilibrium E) the temperature, pressure and density are all numerically equal

Q: If the zeroth law of thermodynamics were not valid, which of the following could not be considered a property of an object? A) Pressure B) Center of mass energy C) Internal energy D) Momentum E) Temperature

Q: The zeroth law of thermodynamics allows us to define A) work B) pressure C) temperature D) thermal equilibrium E) internal energy

Q: Suppose object C is in thermal equilibrium with object A and with object B. The zeroth law of thermodynamics states: A) that C will always be in thermal equilibrium with both A and B B) that C must transfer energy to both A and B C) that A is in thermal equilibrium with B D) that A cannot be in thermal equilibrium with B E) nothing about the relationship between A and B

Q: A balloon is filled with cold air and placed in a warm room. It is NOT in thermal equilibrium with the air of the room until A) it rises to the ceiling B) it sinks to the floor C) it stops expanding D) it starts to contract E) none of the above

Q: When two gases separated by a diathermal wall are in thermal equilibrium with each other: A) only their pressure must be the same B) only their volumes must be the same C) they must have the same number of particles D) they must have the same pressure and the same volume E) only their temperatures must be the same

Q: If two objects are in thermal equilibrium with each other A) they cannot be moving B) they cannot be undergoing an elastic collision C) they cannot have different pressures D) they cannot be at different temperatures E) they cannot be falling in the Earth's gravitational field

Q: What is the limiting low temperature of a physical object?A) there is no limiting low temperatureB) 0 KC) 0 CD) 0 FE) -100 C

Q: In constructing a thermometer it is NECESSARY to use a substance that: A) expands with rising temperature B) expands linearly with rising temperature C) will not freeze D) will not boil E) undergoes some change when heated or cooled

Q: The international standard thermometer is kept: A) near Washington, D.C. B) near Paris, France C) near the north pole D) near Rome, Italy E) nowhere (there is none)

Q: To help keep buildings cool in the summer, dark colored window shades have been replaced by light colored shades. This is because light colored shades: A) are more pleasing to the eye B) absorb more sunlight C) reflect more sunlight D) transmit more sunlight E) have a lower thermal conductivity

Q: An electric stove burner of diameter 20 cm is at a temperature of 250 C. If , at what rate is the burner radiating energy? Assume the emissivity A) 4 WB) 80 WC) 320 WD) 1600 WE) 8000 W

Q: An iron stove, used for heating a room by radiation, is more efficient if: A) its inner surface is highly polished B) its inner surface is covered with aluminum paint C) its outer surface is covered with aluminum paint D) its outer surface is rough and black E) its outer surface is highly polished

Q: Thermal energy can be transferred by convection: A) only in solids B) only in liquids C) only in gases D) through a vacuum E) in either liquids or gases

Q: A homeowner purchases insulation for her attic rated at R-15. She wants the attic insulated to R-30. If the insulation she purchased is 10 cm thick, what thickness does she need to use? A) 10 cm B) 15 cm C) 20 cm D) 30 cm E) 40 cm

Q: The diagram shows four slabs of different materials with equal thickness, placed side by side. Heat flows from left to right and the steady-state temperatures of the interfaces are given. Rank the materials according to their rates of thermal conduction, smallest to largest. A) 1, 2, 3, 4 B) 2, 1, 3, 4 C) 1, 2, 4, 3 D) 3, 4, 2, 1 E) all are equal

Q: The diagram shows four slabs of different materials with equal thickness, placed side by side. Heat flows from left to right and the steady-state temperatures of the interfaces are given. Rank the materials according to their thermal conductivities, smallest to largest. A) 1, 2, 3, 4 B) 2, 1, 3, 4 C) 1, 2, 4, 3 D) 3, 4, 2, 1 E) 4, 3, 2, 1

Q: The rate of heat flow through a slab is Pcond. If the slab thickness is doubled, its cross-sectional area is halved, and the temperature difference across it is doubled, then the rate of heat flow becomes: A) 2Pcond B) Pcond/2 C) Pcond D) Pcond/8 E) 8Pcond

Q: The rate of heat flow by conduction through a slab does NOT depend upon the: A) temperature difference between opposite faces of the slab B) thermal conductivity of the slab C) slab thickness D) cross-sectional area of the slab E) specific heat of the slab

Q: The speed of sound is 340 m/s. A plane flies horizontally at an altitude of 10,000 m and a speed of 400 m/s. When an observer on the ground hears the sonic boom the horizontal distance from the point on its path directly above the observer to the plane is (assume the speed of sound does not change with altitude): A) 5800 m B) 6100 m C) 8400 m D) 12,000 m E) 16,000 m

Q: If the speed of sound is 340 m/s a plane flying at 400 m/s creates a conical shock wave with an apex half angle of:A) 0 (no shock wave)B) 32°C) 40°D) 50°E) 58°

Q: If the speed of sound is 340 m/s a plane flying at 400 m/s has a Mach number of: A) 0.85 B) 1.2 C) 1.4 D) 1.7 E) 400

Q: A plane produces a sonic boom only when: A) its speed changes from being slower than the speed of sound to being faster than the speed of sound B) it emits sound waves of high frequency C) it flies at high altitudes D) it flies on a curved path E) it flies faster than the speed of sound

Q: The diagram shows four situations in which a source of sound S and a detector D are either moving or stationary. The arrows indicate the directions of motion. The speeds (when not zero) are all the same. (Note that the detector in situation 3 is stationary). Rank the situations according to the apparent frequency of the source, lowest to highest. A) 1, 2, 3, 4 B) 4, 3, 2, 1 C) 1, 3, 4, 2 D) 2, 1, 4, 3 E) None of the above

Q: In each of the following two situations a source emits sound with a frequency of 1000 Hz. In situation I the source is moving at 100 m/s toward an observer at rest. In situation II the observer is moving at 100 m/s toward the source, which is stationary. The speed of sound is 340 m/s. The frequencies heard by the observers in the two situations are: A) I: 1417 Hz; II: 1294 Hz B) I: 1417 Hz; II: 1417 Hz C) I: 1294 Hz; II: 1294 Hz D) I: 773 Hz; II: 706 Hz E) I: 773 Hz; II: 773 Hz

Q: A source emits sound with a frequency of 1000 Hz. It is moving at 20 m/s toward a stationary reflecting wall. If the speed of sound is 340 m/s an observer at rest directly behind the source hears a beat frequency of: A) 3.0 Hz B) 55 Hz C) 63 Hz D) 114 Hz E) 118 Hz

Q: A source emits sound with a frequency of 1000 Hz. It and an observer are moving toward each other, each with a speed of 100 m/s. If the speed of sound is 340 m/s, the observer hears sound with a frequency of: A) 290 Hz B) 540 Hz C) 1000 Hz D) 1800 Hz E) 3400 Hz

Q: A source emits sound with a frequency of 1000 Hz. Both it and an observer are moving in the same direction with the same speed, 100 m/s. If the speed of sound is 340 m/s, the observer hears sound with a frequency of: A) 290 Hz B) 540 Hz C) 1000 Hz D) 1800 Hz E) 3400 Hz

Q: A stationary source emits a sound wave of frequencyf.If it were possible for a man to travel toward the source at the speed of sound, he would observe the emitted sound to have a frequency of: A) 0 B) f/2 C) 2f/3 D) 2f E) infinity

Q: A stationary source S generates circular outgoing waves on a lake. The wave speed is 5.0 m/s and the crest-to-crest distance is 2.0 m. A person in a motor boat heads directly toward S at 3.0 m/s. To this person, the frequency of these waves is: A) 1.0 Hz B) 1.5 Hz C) 2.0 Hz D) 4.0 Hz E) 8.0 Hz

Q: A stationary source generates 5.0 Hz water waves whose speed is 2.0 m/s. A boat is approaching the source at 1.0 m/s. The frequency of these waves, as observed by a person in the boat, is: A) 2.5 Hz B) 5.0 Hz C) 7.5 Hz D) 15 Hz E) 30 Hz

Q: The Doppler shift formula for the frequency detected is wheref ' is the frequency emitted, vis the speed of sound, vDis the speed of the detector, and vsis the speed of the source. Suppose the source is traveling at 5 m/s away from the detector, the detector is traveling at 7 m/s toward the source, and there is a 3 m/s wind blowing from the source toward the detector. The values that should be substituted into the Doppler shift equation are: A) vD= 7 m/s and vs= 5 m/s B) vD= 10 m/s and vs= 8 m/s C) vD= 4 m/s and vs= 2 m/s D) vD= 10 m/s and vs= 2 m/s E) vD= 4 m/s and vs= 8 m/s

Q: The rise in pitch of an approaching siren is an apparent increase in its: A) speed B) amplitude C) frequency D) wavelength E) number of overtones

Q: Two stationary tuning forks (350 and 352 Hz) are struck simultaneously. The resulting sound is observed to: A) beat with a frequency of 2 beats/s B) beat with a frequency of 351 beats/s C) be loud but not beat D) be Doppler shifted by 2 Hz E) have a frequency of 702 Hz

Q: Two identical strings, A and B, have nearly the same tension. When they both vibrate in their fundamental resonant modes, there is a beat of 3 Hz. When string B is tightened slightly, to increase the tension, the beat frequency becomes 6 Hz. This means: A) that before tightening A had a higher frequency than B, but after tightening, B has a higher frequency than A B) that before tightening B had a higher frequency than A, but after tightening, A has a higher frequency than B C) that before and after tightening A has a higher frequency than B D) that before and after tightening B has a higher frequency than A E) none of the above

Q: Two identical tuning forks vibrate at 256 Hz. One of them is then loaded with a drop of wax, after which 6 beats per second are heard. The frequency of the loaded tuning fork is: A) 250 Hz B) 253 Hz C) 256 Hz D) 259 Hz E) 262 Hz

Q: When listening to tuning forks of frequency 256 Hz and 260 Hz, one hears the following number of beats per second: A) 0 B) 2 C) 4 D) 8 E) 258

Q: The largest number of beats per second will be heard from which pair of tuning forks? A) 200 and 201 Hz B) 256 and 260 Hz C) 534 and 540 Hz D) 763 and 774 Hz E) 8420 and 8422 Hz

Q: In order for two sound waves to produce audible beats, it is essential that the two waves have: A) the same amplitude B) the same frequency C) the same number of overtones D) slightly different amplitudes E) slightly different frequencies

Q: To produce beats it is necessary to use two waves: A) traveling in opposite directions B) of slightly different frequencies C) of equal wavelengths D) of equal amplitudes E) whose ratio of frequencies is an integer

Q: Beats in sound occur when: A) two waves of the same frequency interfere B) two waves of slightly different frequency interfere C) a reflected wave interferes with an incident wave D) waves travel in two media having slightly different sound velocities E) source and observer are in relative motion

Q: The valves of a trumpet and the slide of a trombone are for the purpose of: A) playing short (staccato) notes B) tuning the instruments C) changing the harmonic content D) changing the length of the air column E) producing gradations in loudness

Q: An organ pipe with both ends open is 0.85 m long. Assuming that the speed of sound is 340 m/s, the frequency of the third harmonic of this pipe is: A) 200 Hz B) 300 Hz C) 400 Hz D) 600 Hz E) none of these

Q: A 200-cm organ pipe with one end open is in resonance with a sound wave of wavelength 270 cm. The pipe is operating in its: A) fundamental frequency B) first harmonic C) second harmonic D) third harmonic E) fourth harmonic

Q: Organ pipe Y (open at both ends) is twice as long as organ pipe X (open at one end) as shown. The ratio of their fundamental frequenciesfX::fYis: A) 1:1 B) 1:2 C) 2:1 D) 1:4 E) 4:1

Q: If the speed of sound is 340 m/s, the shortest pipe,closed at one end, which resonates at 218 Hz is: A) 39 cm B) 78 cm C) 1.6 m D) 3.1 m E) 6.2 m

Q: The speed of sound in air is 340 m/s. The shortest air column, closed at one end, which will resonate to a 512 Hz tuning fork is approximately: A) 4.2 cm B) 8.3 cm C) 17 cm D) 33 cm E) 66 cm

Q: The lowest tone produced by a certain organ comes from a 3.0-m pipe with both ends open. If the speed of sound is 340 m/s, the frequency of this tone is approximately: A) 14 Hz B) 28 Hz C) 57 Hz D) 110 Hz E) 230 Hz

Q: If the speed of sound is 340 m/s, the two lowest frequencies of an 0.5 m organ pipe, closed at one end, are approximately: A) 170 and 340 Hz B) 170 and 510 Hz C) 340 and 680 Hz D) 340 and 1020 Hz E) 57 and 170 Hz

Q: Five organ pipes are described below. Which one has the highest fundamental frequency? A) A 2.3-m pipe with one end open and the other closed B) A 3.3-m pipe with one end open and the other closed C) A 1.6-m pipe with both ends open D) A 3.0-m pipe with both ends open E) a pipe in which the displacement nodes are 5 m apart

Q: An organ pipe with one end closed and the other open has length L. Its fundamental frequency is proportional to: A) L B) 1/L C) 1/L2 D) L2 E)

Q: A vibrating tuning fork is held over a water column with one end closed and the other open. As the water level is allowed to fall, a loud sound is heard for water levels separated by 17 cm. If the speed of sound in air is 340 m/s, the frequency of the tuning fork is: A) 58 Hz B) 500 Hz C) 1000 Hz D) 2000 Hz E) 5800 Hz

Q: A 1024 Hz tuning fork is used to obtain a series of resonance levels in a gas column of variable length, with one end closed and the other open. The length of the column changes by 20 cm from resonance to resonance. From this data, the speed of sound in this gas is: A) 20 m/s B) 51 m/s C) 102 m/s D) 205 m/s E) 410 m/s

Q: A column of argon is open at one end and closed at the other. The shortest length of such a column that will resonate with a 200 Hz tuning fork is 42.5 cm. The speed of sound in argon must be: A) 85.0 m/s B) 170 m/s C) 340 m/s D) 470 m/s E) 940 m/s

Q: A tuning fork produces sound waves of wavelength in air. This sound is used to cause resonance in an air column, closed at one end and open at the other. The length of this column CANNOT be:

Q: A standing wave in a pipe has nodes that are 1.2 m apart. What is the wavelength of the wave? A) 0.6 m B) 1.2 m C) 1.8 m D) 2.4 m E) cannot tell without knowing which harmonic it is

Q: Two notes are an octave apart. The ratio of their frequencies is: A) 8 B) 10 C) D) 2 E)

Q: The "A" on a trumpet and a clarinet have the same pitch, but the two are clearly distinguishable. Which property is most important in enabling one to distinguish between these two instruments? A) intensity B) fundamental frequency C) displacement amplitude D) pressure amplitude E) harmonic content

Q: An organ pipe with one end open and the other closed is operating at one of its resonant frequencies. The open and closed ends are respectively: A) pressure node, pressure node B) pressure node, displacement node C) displacement antinode, pressure node D) displacement node, displacement node E) pressure antinode, pressure antinode

Q: Two pipes are each open at one end and closed at the other. Pipe A has length Land pipe B has length 2L. Which harmonic of pipe B matches in frequency the fundamental of pipe A? A) The fundamental B) The second C) The third D) The fourth E) There are none

Q: You are listening to an "A" note played on a violin string. Let the subscript "s" refer to the violin string and "a" refer to the air. Then:E) linear density of string = volume density of air

Q: If the sound level is increased by 10 db the intensity increases by a factor of: A) 2 B) 5 C) 10 D) 20 E) 100