PS 160 Unit 2: Sound and Hearing, Temperature and Heat, and Thermal Properties of Matter
The tension in each of two strings is adjusted so that both vibrate at exactly 666 Hz. The tension in one of the strings is then increased slightly. As a result, six beats per second are heard when both strings vibrate. What is the new frequency of the string that was tightened? A) 672 Hz B) 660 Hz C) 669 Hz D) 663 Hz
A
A person is hearing two sound waves simultaneously. One has a period of 1.50 ms and the other one a period of 1.54 ms. What is the period of the beat due to these two waves? A) 0.040 ms B) 1.5 ms C) 3.0 ms D) 58 ms E) 330 ms
D
A certain metal has a coefficient of linear expansion of 2.00 × 10-5 K-1. It has been kept in a laboratory oven at 325°C for a long time. It is now removed from the oven and placed in a freezer at ‐145°C. After it has reached freezer temperature, the percent change in its density during this process is closest to A) +2.90%. B) ‐2.90%. C) +2.74%. D) ‐2.74%. E) It is not possible to tell without knowing the mass and original volume of the metal.
A
A chunk of ice (T = ‐20°C) is added to a thermally insulated container of cold water (T = 0°C). What happens in the container? A) The ice melts until thermal equilibrium is established. B) The water cools down until thermal equilibrium is established. C) Some of the water freezes and the chunk of ice gets larger. D) None of the above things happen.
C
A rod has a length 2.00000 m at 10.0°C. The length of the rod increases to 2.00060 m when the temperature increases to 30.0°C. What is the coefficient of linear expansion of the material from which the rod is made? A) 2.0 × 10-5/K B) 2.5 × 10-5/K C) 1.5 × 10-5/K D) 1.0 × 10-3/K E) 1.0 × 10-5/K
C
A supersonic plane passes overhead at a speed of 500 m/s. If you hear the sonic boom (shock wave) 4.00 s after the plane is directly overhead, at what altitude is the plane flying? Assume the speed of sound in air is 340 m/s. A) 1.36 km B) 2.16 km C) 1.85 km D) 2.45 km E) The plane is not flying fast enough to produce a shock wave.
C
A carousel that is 5.00 m in radius has a pair of 600-Hz sirens mounted on posts at opposite ends of a diameter. The carousel rotates with an angular velocity of 0.800 rad/s. A stationary listener is located at a distance from the carousel. The speed of sound is 350 m/s. The maximum beat frequency of the sirens at the position of the listener is closest to A) 6 Hz. B) 8 Hz. C) 10 Hz. D) 12 Hz. E) 14 Hz.
E
A sample of an ideal gas is slowly compressed to one‐half its original volume with no change in pressure. If the original root‐mean‐square speed (thermal speed) of the gas molecules was V, the new speed is A) V. B) 2V. C)SQRT( 2V). D) V/2. E)V/ SQRT(2)
E
Two people are talking at a distance of 3.0 m from where you are and you measure the sound intensity as 1.1 × 10-7 W/m2. Another student is 4.0 m away from the talkers. What sound intensity does the other student measure? Assume that the sound spreads out uniformly and undergoes no significant reflections or absorption. A) 6.2 × 10-8 W/m2 B) 1.5 × 10-7 W/m2 C) 8.3 × 10-8 W/m2 D) 7.8 × 10-7 W/m2 E) 2.5 × 10-8 W/m2
I_2 = (1.1 x 10^-7 2/m^2)(3.0m/4.0m)^2 =6.1875 x 10^-8 w/m^2
When a vapor condenses A) the temperature of the substance increases. B) the temperature of the substance decreases. C) heat energy leaves the substance. D) heat energy enters the substance.
C
A 2.00-m long piano wire with a mass per unit length of 12.0 g/m is under a tension of 8.00 kN. What is the frequency of the fundamental mode of vibration of this wire? length of the string L = 2 m mass per unit length u = 12 g/m = 12*10^-3 kg/m tension T = 8*10^3 N fundamental frequency f = 1/(2L)*sqrt(T/u) fundamental frequency f = 1/(2*2)*sqrt(8000/(12*10^-3)) = A) 204 Hz B) 102 Hz C) 408 Hz D) 510 Hz E) 153 Hz
A
Two in-phase loudspeakers that emit sound with the same frequency are placed along a wall and are separated by a distance of 8.00 m. A person is standing 12.0 m away from the wall, equidistant from the loudspeakers. When the person moves 3.00 m parallel to the wall, she experiences destructive interference for the second time. What is the frequency of the sound? The speed of sound in the room is 343 m/s. CAREFUL! The distance to the wall is NOT much greater than the distance between the speakers. A) 278 Hz B) 422 Hz C) 452 Hz D) 562 Hz E) 694 Hz
A
78) A jet aircraft, in level flight at constant speed, is observed directly over head. A sonic boom is heard 13.0 s later, at which time the line of sight to the aircraft forms a 51° angle with respect to the horizontal. The speed of sound is 325 m/s. The altitude of the aircraft is closest to A) 6700 m. B) 5400 m. C) 8300 m. D) 2700 m. E) 13,000 m.
A
A 0.25-m string, vibrating in its sixth harmonic, excites a 0.96-m pipe that is open at both ends into its second overtone resonance. The speed of sound in air is 345 m/s. The common resonant frequency of the string and the pipe is closest to Resonant frequency of pipe for both open ends , f= nv/2L Where n= Harmonic no. 2nd overtone = 3rd harmonic hence n= 3 f= 2v/2L = (3*345)/(2*0.96) = A) 540 Hz. B) 360 Hz. C) 450 Hz. D) 630 Hz. E) 700 Hz.
A
A 400-g piece of metal at 120.0°C is dropped into a cup containing 450 g of water at 15.0°C. The final temperature of the system is measured to be 40.0°C. What is the specific heat of the metal, assuming no heat is exchanged with the surroundings or the cup? The specific heat of water is 4190 J/(kg·K). A) 1470 J/(kg · K) B) 2830 J/(kg · K) C) 3420 J/(kg · K) D) 3780 J/(kg · K) E) 4280 J/(kg · K)
A
An 80-g aluminum calorimeter contains 380 g of water at an equilibrium temperature of 20°C. A 120-g piece of metal, initially at 352°C, is added to the calorimeter. The final temperature at equilibrium is 32°C. Assume there is no external heat exchange. The specific heats of aluminum and water are 910 J/kg·K and 4190 J/kg·K, respectively. The specific heat of the metal is closest to A) 520 J/kg · K. B) 480 J/kg · K. C) 390 J/kg · K. D) 350 J/kg · K. E) 560 J/kg · K.
A
Heat is added to a 2.0 kg piece of ice at a rate of 793.0 kW. How long will it take for the ice to melt if it was initially at 0.00°C? (The latent heat of fusion for water is 334 kJ/kg and its latent heat of vaporization is 2260 kJ/kg.) A) 0.84 s B) 530,000 s C) 4.7 s D) 670 s
A
At a distance of 2.00 m from a point source of sound, the intensity level is 80.0 dB. What will be the intensity level at a distance of 4.00 m from this source? The lowest detectable intensity is 1.0 × 10-12 W/m2. A) 77.0 dB B) 74.0 dB C) 60.0 dB D) 40.0 dB E) 20.0 dB
B
Two in-phase loudspeakers that emit sound with the same frequency are placed along a wall and are separated by a distance of 5.00 m. A person is standing 12.0 m away from the wall, equidistant from the loudspeakers. When the person moves 1.00 m parallel to the wall, she experiences destructive interference for the first time. What is the frequency of the sound? The speed of sound in air is 343 m/s. A) 211 Hz B) 256 Hz C) 422 Hz D) 512 Hz E) 674 Hz
C
Two steel spheres are made of the same material and have the same diameter, but one is solid and the other is hollow. If their temperature is increased by the same amount A) the solid sphere becomes bigger than the hollow one. B) the hollow sphere becomes bigger than the solid one. C) the two spheres remain of equal size. D) the solid sphere becomes heavier and the hollow one becomes lighter. E) the solid sphere becomes lighter and the hollow one becomes heavier.
C
You are driving along a highway at 35.0 m/s when you hear the siren of a police car approaching you from behind and you perceive the frequency as 1310 Hz. You are relieved that he is in pursuit of a different speeder when he continues past you, but now you perceive the frequency as 1240 Hz. What is the frequency of the siren in the police car? The speed of sound in air is 343 m/s. A) 1300 Hz B) 1320 Hz C) 1270 Hz D) 1360 Hz E) 1370 Hz
C
A boy on a bicycle approaches a brick wall as he sounds his horn at a frequency 400.00 Hz. The sound he hears reflected back from the wall is at a frequency 408.00 Hz. At what is the speed is the boy riding his bicycle toward the wall? Assume the speed of sound in air is 340 m/s. A) 3.68 m/s B) 333 m/s C) 6.67 m/s D) 6.80 m/s E) 3.37 m/s
E
A 0.10-m3 gas tank holds 5.0 moles of nitrogen gas (N2), at a temperature of 370 K. The atomic mass of nitrogen is 14 g/mol, the molecular radius is 3.0 × 10-10 m, and the Boltzmann constant is 1.38 × 10-23 J/K. The root-mean-square speed (thermal speed) of the molecules is closest to ms speed = sqrt(3RT/M) ; where M = mass of 1 mole of nitrogen in kg = 0.028 kg R = 8.314 and T = temperature in Kelvin = 350 K A) 570 m/s. B) 810 m/s. C) 410 m/s. D) 22 m/s. E) 99 m/s.
A
A 200-g metal container, insulated on the outside, holds 100 g of water in thermal equilibrium at 22.00°C. A 21-g ice cube, at the melting point, is dropped into the water, and when thermal equilibrium is reached the temperature is 15.00°C. Assume there is no heat exchange with the surroundings. For water, the specific heat is 4190 J/kg · K and the heat of fusion is 3.34 × 105 J/kg. The specific heat for the metal is closest to mass of metal , m = 200 gm = 0.2 Kg mass of water , mw = 100 gm = 0.100 Kg T = 22 degree C let the specific heat of metal is Sm heat lost by metal + heat lost by water = heat gain by ice 0.1 * 4186 * (22 -15) + 0.2 * Sm * (22 - 15) = 0.021 * (334 *10^3 + 4186 * 15) solving for Sm Sm = A) 3850 J/kg · K. B) 2730 J/kg · K. C) 4450 J/kg · K. D) 4950 J/kg · K. E) 5450 J/kg · K.
A
A 3.2-L volume of neon gas (Ne) is at a pressure of 3.3 atm and a temperature of 330 K. The atomic mass of neon is 20.2 g/mol, Avogadro's number is 6.022 10 23 molecules/mol, and the ideal gas constant is R = 8.314 J/mol · K = 0.0821 L · atm/mol · K. The mass of the neon gas is closest to A) 7.9 × 10-3 kg. B) 4.6 × 10-3 kg. C) 3.8 kg. D) 7.8 kg. E) 7.8 × 102 kg.
A
A 5.0-liter gas tank holds 1.4 moles of helium (He) and 0.70 moles of oxygen (O2), at a temperature of 260 K. The atomic masses of helium and oxygen are 4.0 g/mol and 16.0 g/mol, respectively. Avogadro's number is 6.022 × 1023 molecules/mol and the Boltzmann constant is 1.38 × 10-23 J/K. The total random translational kinetic energy of the gas in the tank is closest to A) 6.8 kJ. B) 6.1 kJ. C) 7.6 kJ. D) 8.3 kJ. E) 9.1 kJ.
A
A block of ice at 0.000°C is added to a well-insulated 147-g aluminum calorimeter cup that holds 200 g of water at 10.0°C. The water and aluminum cup are in thermal equilibrium, and the specific heat of aluminum is 910 J/(kg·K). If all but 2.00 g of ice melt, what was the original mass of the block of ice? The specific heat of water is 4190 J/(kg·K), its latent heat of fusion is 334 kJ/kg, and its latent heat of vaporization is 2260 kJ/kg. A) 31.1 g B) 35.6 g C) 38.8 g D) 42.0 g E) 47.6 g
A
A cold trap is set up to cause molecules to linger near the suction in a vacuum system. If the cold trap has an effective volume of 0.200L and is maintained at 13.0K, how many molecules are in it at 10.0 Pa of pressure? (Avogadroʹs number is 6.022 × 1023 molecules/mol, and the universal gas constant is 8.314 J/mol•K. Assume the behavior of an ideal gas.) A) 1.11 × 1019 molecules B) 1.10 × 1022 molecules C) 7.71 × 1020 molecules D) 7.71 × 1023 molecules
A
A hot air balloon has a volume of 2.00 × 103 m3 when fully inflated, and the air inside the balloon is always at atmospheric pressure of 1.01 × 105 Pa because of the large opening used to fill the balloon and heat the air inside it. What is the mass of hot air inside the balloon if its temperature is 120°C? The universal gas constant is 8.314 J/mol•K. (Assume a molecular weight of 28.8 g/mol for air.) A) 1780 kg B) 5850 kg C) 203 kg D) 62.0 kg
A
A sealed 26-m3 tank is filled with 2000 moles of oxygen gas (O2) at an initial temperature of 270 K. The gas is heated to a final temperature of 460 K. The ATOMIC mass of oxygen is 16.0 g/mol, and the ideal gas constant is R = 8.314 J/mol · K = 0.0821 L · atm/mol · K. The final pressure of the gas is closest to A) 0.29 MPa. B) 0.31 MPa. C) 0.33 MPa. D) 0.34 MPa. E) 0.36 MPa.
A
A sealed 89-m3 tank is filled with 6000 moles of oxygen gas (O2) at an initial temperature of 270 K. The gas is heated to a final temperature of 350 K. The ATOMIC mass of oxygen is 16.0 g/mol, and the ideal gas constant is R = 8.314 J/mol · K = 0.0821 L · atm/mol · K. The initial pressure of the gas is closest to A) 0.15 MPa. B) 0.17 MPa. C) 0.19 MPa. D) 0.13 MPa. E) 0.11 MPa.
A
An oxygen molecule falls in a vacuum. From what height must it fall so that its kinetic energy at the bottom equals the average energy of an oxygen molecule at 800 K? (The Boltzmann constant is 1.38 × 10-23 J/K, the molecular weight of oxygen is 32.0 g/mol, and Avogadro's number is 6.022 × 1023 molecules/mol.) rms speed=sqrt(3RT/M)= sqrt(2gh) ==> (3RT/M)=(2gh) at 800K ==> h= 3RT/2Mg=3*8.31*800/(2*0.032*9.8)=31798 m= 3 A) 31.8 km B) 10.6 km C) 21.1 km D) 42.3 km
A
At what temperature would the root-mean-square speed (thermal speed) of oxygen molecules be 13.0 m/s? Assume that oxygen approximates an ideal gas. The mass of one O 2 molecule is 5.312 x 10-26 kg. The Boltzmann constant is 1.38 × 10-23 J/K. A) 0.217 K B) 1800 K C) 5410 K D) 0.0666 K
A
Dust particles are pulverized rock, which has density 2500 kg/m 3. They are approximately spheres 20 μm in diameter. Treating dust as an ideal gas, what is the root-mean-square speed (thermal speed) of a dUst particle at 400°C? (The Boltzmann constant is 1.38 × 10-23 J/K.) A) 5.2 × 10-5 m/s B) 1.7 × 10-5 m/s C) 3.0 × 10-5 m/s D) 7.3 × 10-5 m/s
A
Sometimes an experiment requires a certain pure gas to be used at reduced pressure. One way to achieve this is to purchase a sealed glass container filled with the gas, and to introduce the gas into a vacuum by attaching the glass container to the vacuum chamber and breaking the tip of the glass container using a metallic bean and a magnet. If the volume of the glass container is 1.0 L and it is at a pressure of 1.0 × 105 Pa and if the vacuum chamber has a volume of 2.0 L, what will the pressure be after the gas, which is to be assumed to be an ideal gas, is released into the vacuum chamber and the temperature has returned to its original value? (Note that the glass container remains part of the system.) A) 33 kPa B) 50 kPa C) 300 kPa D) 200 kPa
A
The figure shows a 50-kg frictionless cylindrical piston that floats on 0.68 mol of compressed air at 30°C. How far does the piston move if the temperature is increased to 300°C? A) 120 cm B) 250 cm C) 130 cm D) 1300 cm
A
The root-mean-square speed (thermal speed) for a certain gas at 100°C is 0.500 km/s. If the temperature of the gas is now increased to 200°C, the root-mean-square (thermal) speed will be closest to Vrms = 0.5 = sqrt(3R373.15 / M) Vrms(new) = sqrt(3R473.15 /M) We divide the both equations to get: Vrms (new) / 0.5 = sqrt(473.15 / 373.15) Therefore, Vrms(new) = 0.563 km/s A) 563 m/s. B) 634 m/s. C) 707 m/s. D) 804 m/s. E) 1000 m/s.
A
What is the average kinetic energy of an ideal gas molecule at 569°C? (The Boltzmann constant is 1.38 × 10-23 J/K.) KEavg = 3kT/2 k = 1.38*10^-23 T = 273 + 569 = 842 K So, KEavg = 3*1.38*10^-23*842/2 A) 1.74 × 10-20 J B) 5.81 × 10-21 J C) 1.18 × 10-17 J D) 3.93 × 10-19 J
A
A 25-L container holds ideal hydrogen (H2) gas at a gauge pressure of 0.25 atm and a temperature of 0°C. What mass of hydrogen gas is in this container? The ATOMIC mass of hydrogen is 1.0 g/mol, the ideal gas constant is R = 8.314 J/mol•K = 0.0821 L · atm/mol · K, and 1.00 atm = 101 kPa. A) 1.4 g B) 2.8 g C) 4.2 g D) 5.6 g E) 6.3 g
B
A cubic box with sides of 20.0 cm contains 2.00 × 1023 molecules of helium with a root-mean-square speed (thermal speed) of 200 m/s. The mass of a helium molecule is 3.40×10-27 kg. What is the average pressure exerted by the molecules on the walls of the container? The Boltzmann constant is 1.38 × 10-23 J/K and the ideal gas constant is R = 8.314 J/mol•K = 0.0821 L · atm/mol · K. A) 3.39 kPa B) 1.13 kPa C) 570 Pa D) 2.26 kPa E) 9.10 Pa
B
A sealed container holds 0.020 moles of nitrogen (N2) gas at a pressure of 1.5 atmospheres and a temperature of 290 K. The atomic mass of nitrogen is 14 g/mol. The Boltzmann constant is 1.38 × 10-23 J/K and the ideal gas constant is R = 8.314 J/mol•K = 0.0821 L · atm/mol · K. The average translational kinetic energy of a nitrogen molecule is closest to A) 4.0 × 10-21 J. B) 6.0 × 10-21 J. C) 8.0 × 10-21 J. D) 10 × 10-21 J. E) 12 × 10-21 J.
B
At 50.0°C, the average translational kinetic energy of a gas molecule is K. If the temperature is now increased to 100.0°C, the average translational kinetic energy of a molecule will be closest to A) 1.07K. B) 1.15K. C) 1.41K. D) 2.00K. E) 4.00K.
B
Two experimental runs are performed to determine the calorimetric properties of an alcohol that has a melting point of ‐10°C. In the first run, a 200-g cube of frozen alcohol, at the melting point, is added to 300 g of water at 20°C in a styrofoam container. When thermal equilibrium is reached, the alcohol-water solution is at a temperature of 5.0°C. In the second run, an identical cube of alcohol is added to 500 g of water at 20°C and the temperature at thermal equilibrium is 10°C. The specific heat of water is 4190 J/kg ·K. Assume that no heat is exchanged with the styrofoam container and with the surroundings. The heat of fusion of the alcohol is closest to A) 5.5 × 104 J/kg B) 6.3 × 104 J/kg C) 7.1 × 104 J/kg D) 7.9 × 104 J/kg E) 8.7 × 104 J/kg
B
A 5.0-liter gas tank holds 1.7 moles of monatomic helium (He) and 1.10 mole of diatomic oxygen (O2), at a temperature of 260 K. The ATOMIC masses of helium and oxygen are 4.0 g/mol and 16.0 g/mol, respectively. What is the ratio of the root -mean-square (thermal) speed of helium to that of oxygen? A) 1.4 B) 2.0 C) 2.8 D) 4.0 E) 5.6
C
A person makes ice tea by adding ice to 1.8 kg of hot tea, initially at 80°C. How many kilograms of ice, initially at 0.00°C, are required to bring the mixture to 10°C? The heat of fusion of ice is 334 kJ/kg, and we can assume that tea has essentially the same thermal properties as water, so its specific heat is 4190 J/(kg·K). A) 1.0 kg B) 1.2 kg C) 1.4 kg D) 1.5 kg E) 1.7 kg
C
A sealed container holds 0.020 moles of nitrogen (N2) gas, at a pressure of 1.5 atmospheres and a temperature of 290 K. The atomic mass of nitrogen is 14.0 g/mol. The Boltzmann constant is 1.38 × 10-23 J/K and the ideal gas constant is R = 8.314 J/mol · K = 0.0821 L · atm/mol · K. The mass density of the gas is closest to A) 0.90 kg/m3. B) 1.3 kg/m3. C) 1.8 kg/m3. D) 2.2 kg/m3. E) 2.6 kg/m3.
C
A weather balloon contains 12.0 m3 of hydrogen gas when the balloon is released from a location at which the temperature is 22.0°C and the pressure is 101 kPa. The balloon rises to a location where the temperature is -30.0°C and the pressure is 20.0 kPa. If the balloon is free to expand so that the pressure of the gas inside is equal to the ambient pressure, what is the new volume of the balloon? Assume that in both cases the hydrogen gas is in thermal equilibrium with the outside air. A) 14.0 m3 B) 2.38 m3 C) 49.9 m3 D) 82.6 m3 E) 4.16 m3
C
How many moles of water (H2O) molecules are in a 4.00 m3 container at a pressure 8.00 × 105 N/m2 and temperature 600°C? The ideal gas constant is R = 8.314 J/mol•K = 0.0821 L · atm/mol · K. A) 7.72 × 1026 mol B) 641 mol C) 441 mol D) 3.86 × 1026 mol E) 2.65 × 1026 mol
C
The root-mean-square speed (thermal speed) of the molecules of a gas is 200 m/s at 23.0°C. At 227°C the root-mean-square speed (thermal speed) of the molecules will be closest to A) 160 m/s B) 330 m/s C) 260 m/s D) 630 m/s E) 2000 m/s
C
Two experimental runs are performed to determine the calorimetric properties of an alcohol that has a melting point of ‐10°C. In the first run, a 200-g cube of frozen alcohol, at the melting point, is added to 300 g of water at 20°C in a styrofoam container. When thermal equilibrium is reached, the alcohol-water solution is at a temperature of 5.0°C. In the second run, an identical cube of alcohol is added to 500 g of water at 20°C and the temperature at thermal equilibrium is 10°C. The specific heat of water is 4190 J/kg ·K. Assume that no heat is exchanged with the styrofoam container and with the surroundings. The specific heat of the alcohol is closest to A) 1700 J/kg·K. B) 1900 J/kg·K. C) 2100 J/kg·K. D) 2300 J/kg·K. E) 2500 J/kg·K.
C
What is the average translational kinetic energy per molecule of an ideal gas at a temperature of 300 K? The Boltzmann constant is 1.38 × 10-23 J/K. A) 1.7 × 10-21 J B) 8.3 × 10-21 J C) 6.2 × 10-21 J D) 2.1 × 10-21 J E) 4.1 × 10-21 J
C
A bag of potato chips contains 2.00 L of air when it is sealed at sea level at a pressure of 1.00 atm and a temperature of 20.0°C. What will be the volume of the air in the bag if you take it with you, still sealed, to the mountains where the temperature is 7.00°C and atmospheric pressure is 70.0 kPa? Assume that the bag behaves like a balloon and that the air in the bag is in thermal equilibrium with the outside air. (1 atm = 1.01 × 105 Pa) A) 4.13 L B) 1.01 L C) 1.38 L D) 2.76 L
D
A carousel that is 5.00 m in radius has a pair of 600-Hz sirens mounted on posts at opposite ends of a diameter. The carousel rotates with an angular velocity of 0.800 rad/s. A stationary listener is located at a distance from the carousel. The speed of sound is 350 m/s. The longest wavelength reaching the listener from the sirens is closest to A) 57.0 cm. B) 57.7 cm. C) 58.3 cm. D) 59.0 cm. E) 59.6 cm.
D
An airplane flying faster than the speed of sound of 340 m/s produces a shock wave that makes an angle of 50° with the direction the plane is flying. What is the speed of the plane? A) 490 m/s B) 530 m/s C) 390 m/s D) 440 m/s E) 405 m/s
D
An ideal gas is at a pressure 1.00 × 105 N/m2 and occupies a volume 2.00 m3. If the gas is compressed to a volume 1.00 m3 while the temperature remains constant, what will be the new pressure in the gas? A) 0.500 × 105 N/m2 B) 4.00 × 105 N/m2 C) 1.00 × 105 N/m2 D) 2.00 × 105 N/m2 E) The answer depends on the mass of the gas particles.
D
What is the mass density of argon gas at pressure 1.00 × 105 N/m2 and at temperature 300 K? The mean atomic mass of argon is 39.948 g/mol and the ideal gas constant is R = 8.314 J/mol •K = 0.0821 L · atm/mol · K. A) 1.40 kg/m3 B) 1.00 kg/m3 C) 1.20 kg/m3 D) 1.60 kg/m3 E) 1.80 kg/m3
D
3.00 moles of an ideal gas at a pressure of 250 kPa are held in a container of volume of 25.0 L. The ideal gas constant is R = 8.314 J/mol•K = 0.0821 L · atm/mol · K, and 1 atm = 1.01 x 105 Pa. The temperature of this gas is closest to P V = n R T T = P V / n R = ((250 * 103/1.01*105) * 25 ) / (3.00 * 0.0821) = 251 K = A) 240°C. B) ‐180°C. C) 480°C. D) ‐1.0°C. E) ‐22°C.
E
An ideal gas is kept in a rigid container that expands negligibly when heated. The gas starts at a temperature of 20.0°C, and heat is added to increase its temperature. At what temperature will its root-mean-square speed (thermal speed) be double its value at 20.0°C? Vrms = sqrt(3kT/m) V2/V1 = sqrt(T2/T1) sqrt(T2/T1) = 2 T2/T1 = 2^2 4 T2 = 4* (20+273) T2 = 1172 k T2 = A) 40.0°C B) 141°C C) 313°C D) 400°C E) 899°C
E
The interior of a refrigerator has a volume of 0.600 m3. The temperature inside the refrigerator in 282 K, and the pressure is 101 kPa. If the molecular weight of air is 29 g/mol, what is the mass of air inside the refrigerator? The ideal gas constant is R = 8.314 J/mol•K = 0.0821 L · atm/mol · K. A) 500 g B) 560 g C) 140 g D) 270 g E) 750 g
E
The root-mean-square speed (thermal speed) of a certain sample of carbon dioxide molecules, with a molecular weight of 44 g/mol, is 396 m/s. What is the root-mean-square speed (thermal speed) of water vapor molecules, with a molecular weight of 18 g/mol, at the same temperature? 396^2 = 3* R*T/ 44 so R*T = 2299968 so for H20 V= (3*R*T/ 18) ^0.5 = A) 253 m/s B) 396 m/s C) 421 m/s D) 506 m/s E) 619 m/s
E
The root-mean-square speed (thermal speed) of the molecules of a gas is 200 m/s at a temperature 23.0°C. What is the mass of the individual molecules? The Boltzmann constant is 1.38 × 10-23 J/K. A) 2.13 × 10-25 kg B) 2.45 × 10-25 kg C) 5.66 × 10-25 kg D) 1.78 × 10-25 kg E) 3.11 × 10-25 kg
E
The walls of an ice chest are made of 2.00-mm-thick insulation having a thermal conductivity 0.00300 W/m·K. The total surface area of the ice chest is 1.20 m2. If 4.00 kg of ice at 0.00°C are placed in the chest and the temperature of the outside surface of the chest is 20.0°C, how long does it take the ice to melt under steady state conditions? The latent heat of fusion of water is 79.6 cal/g = 334 kJ/kg. A) 4.22 h B) 22.1 h C) 17.6 h D) 1.33 d E) 10.3 h Answer:
E
A pipe is 0.90 m long and is open at one end but closed at the other end. If it resonates with a tone whose wavelength is 0.72 m, what is the wavelength of the next higher overtone in this pipe? A) 0.36 m B) 0.40 m C) 0.45 m D) 0.51 m E) 0.58 m
D
If the temperature of an iron sphere is increased A) its density will increase. B) its volume will decrease. C) its density will decrease. D) its mass will decrease. E) its density will remain unchanged.
C
The exterior of a supersonic airplane is made of aluminum, which has a coefficient of linear expansion of 24 × 10-6 K-1. At 15°C, the plane measures 62.1 m in length. When the plane is in flight, friction with the air increases the temperature of the exterior skin to 200°C. What is the change in the length of the outer skin of the plane? A) 20 cm B) 24 cm C) 28 cm D) 32 cm E) 36 cm
C
A heavy stone of mass m is hung from the ceiling by a thin 8.25-g wire that is 65.0 cm long. When you gently pluck the upper end of the wire, a pulse travels down the wire and returns 7.84 ms later, having reflected off the lower end. The speed of sound in the room is 344 m/s, and the stone is heavy enough to prevent the lower end of the wire from moving. If the wire is vibrating in its second overtone, what is the wavelength of the sound it will produce? A) 0.217 m B) 0.433 m C) 0.650 m D) 0.899 m E) 1.35 m
D
A blacksmith is flattening a steel plate that measures 10 cm × 15 cm × 1 mm. He has heated the plate to 900 K. If the emissivity of the plate is 0.75, what is the total rate at which it radiates energy? The Stefan-Boltzmann constant is 5.670 × 10-8 W/m2 · K4. Ignore any heat it receives from the surroundings. radiation intensity = sET^4 = 27903 w/m^2, where Stefan constant s = 5.67040D-08 w/m^2-K^4 the plate is 10cm X 15cm X 1mm. The plate radiating area (both sides + edge) = 2*0.1*0.15 + 0.001*0.5 = 0.0305 m^2, so the radiated power = 0.0305*27903 = A) 360 W B) 760 W C) 790 W D) 850 W E) 880 W
D
A concrete wall of a cold storage room measures 3.0 m high, 5.0 m wide, and 20 cm thick. The room temperature is maintained at ‐10°C and the outside temperature is 20°C The inside wall is to be covered by a layer of wood in order to reduce the rate of heat loss through the wall BY 90 percent. The thermal conductivities of concrete and wood are 0.80 W/m ·K and 0.040 W/m·K, respectively. Under steady state conditions, the thickness of the layer of wood required is closest to A) 60 mm. B) 70 mm. C) 80 mm. D) 90 mm. E) 100 mm.
D
A cube at 100.0°C radiates heat at a rate of 80.0 J/s. If the length of each side is cut in half, the rate at which it will now radiate is closest to A) 56.6 J/s. B) 40.0 J/s. C) 28.3 J/s. D) 20.0 J/s. E) 10.0 J/s.
D
If you add 700 kJ of heat to 700 g of water at 70.0°C, how much water is left in the container? The latent heat of vaporization of water is 2.26 × 106 J/kg and its specific heat is is 4190 J/(kg ·K). A) 429 g B) 258 g C) 340 g D) 600 g E) none
A
It is necessary to determine the specific heat of an unknown object. The mass of the object is measured to be 199.0 g. It is determined experimentally that it takes 16.0 J to raise the temperature 10.0°C. Find the specific heat of the object. A) 8.04 J/kg · K B) 1600 J/kg · K C) 0.00120 J/kg · K D) 3.18 × 106 J/kg · K
A
A 406.0 kg copper bar is put into a smelter for melting. The initial temperature of the copper is 300.0 K. How much heat must the smelter produce to completely melt the copper bar? (The specific heat for copper is 386 J/kg•K, the heat of fusion for copper is 205 kJ/kg, and its melting point is 1357 K.) A) 2.49 × 105 kJ B) 1.66 × 1011 kJ C) 1.66 × 108 kJ D) 2.96 × 105 kJ
A
A 648-g empty iron kettle is put on a stove. How much heat. in joules. must it absorb to raise its temperature from 15.0°C to 37.0°C? (The specific heat for iron is 113 cal/kg•C°, 1 cal = 4.190 J) A) 6740 J B) 11,300 J C) 1610 J D) 16,100 J
A
A 905-g meteor impacts the earth at a speed of 1629 m/s. If all of its energy is entirely converted to heat in the meteor, what will be the resulting temperature rise of the meteor, assuming it does not melt? The specific heat for the meteor material is 472 J/kg·K, which is about the same as that of iron. A) 2810°C B) 2,540,000°C C) 3.10°C D) 11,700°C
A
A brass rod is 40.1 cm long and an aluminum rod is 79.3 cm long when both rods are at an initial temperature of 0°C. The rods are placed in line with a gap of 0.60 cm between them, as shown in the figure. The distance between the far ends of the rods is maintained at 120.0 cm throughout. The temperature of both rods is raised until the two rods are barely in contact. The coefficients of linear expansion of brass and aluminum are 2.0 × 10-5 K-1 and 2.4 × 10-5 K-1, respectively. The temperature at which contact of the rods barely occurs is closest to A) 220°C. B) 210°C. C) 200°C. D) 230°C. E) 240°C.
A
A container is filled with a mixture of helium (light molecules) and oxygen (heavy molecules) gases. A thermometer in the container reads 22°C. Which gas molecules have the greater average kinetic energy? A) It is the same for both of the gases because the temperatures are the same. B) The oxygen molecules do because they are diatomic. C) The oxygen molecules do because they are more massive. D) The helium molecules do because they are less massive. E) The helium molecules do because they are monatomic.
A
A glass flask has a volume of 500 mL at a temperature of 20°C. The flask contains 492 mL of mercury at 20°C. The temperature of the mercury and flask is raised until the mercury reaches the 500 mL reference mark. The coefficients of volume expansion of mercury and glass are 18 × 10-5 K-1 and 2.0 × 10-5 K-1, respectively. The temperature at which this occurs is closest to A) 122°C. B) 112°C. C) 102°C. D) 110°C. E) 132°C.
A
A glass window pane is 2.7 m high, 2.4 m wide, and 2.0 mm thick. The temperature at the inner surface of the glass is 22°C and at the outer surface 4.0°C. How much heat is lost each hour through the window under steady state conditions? A) 1.7 × 108 J B) 1.7 × 105 J C) 4.7 × 104 J D) 4.7 × 101 J E) 1.7 × 106 J
A
Suppose that a steel bridge, 1000 m long, was built without any expansion joints and that only one end of the bridge was held fixed. What would the difference in the length of the bridge be between winter and summer, taking a typical winter temperature as 0.00°C, and a typical summer temperature as 40°C? The coefficient of thermal expansion of steel is 10.5 × 10-6 K-1. A) 0.42 m B) 0.11 mm C) 0.11 m D) 0.42 mm E) 0.37 cm
A
A heat-conducting rod, 0.90 m long, is made of an aluminum section that is 0.10 m long, and a copper section that is 0.80 m long. Both sections have cross-sectional areas of 0.00040 m2. The aluminum end is maintained at a temperature of 40°C and the copper end is at 150°C.. The thermal conductivity of aluminum is 205 W/m·K and of copper is 385 W/m·K. Steady-state has been reached, and no heat is lost through the well-insulated sides of the rod. The temperature of the aluminum-copper junction in the rod is closest to A) 61°C. B) 58°C. C) 56°C. D) 54°C. E) 52°C.
A
A heat-conducting rod, 1.40 m long, is made of an aluminum section that is 0.50 m long and a copper section that is 0.90 m long. Both sections have cross-sectional areas of 0.00040 m2. The aluminum end and the copper end are maintained at temperatures of 40°C and 280°C, respectively. The thermal conductivity of aluminum is 205 W/m·K of copper is 385 W/m·K. The rate at which heat is conducted in the rod is closest to A) 20 W. B) 18 W. C) 23 W. D) 25 W. E) 28 W.
A
A howler monkey is the loudest land animal and, under some circumstances, can be heard up to a distance of 5.0 km. Assume the acoustic output of a howler to be uniform in all directions and that the threshold of hearing is 1.0 × 10-12 W/m2. The acoustic power emitted by the howler is closest to A) 0.31 mW. B) 0.11 mW. C) 1.1 mW. D) 3.2 mW. E) 11 mW.
A
A jet aircraft, in level flight at constant speed, is observed directly overhead. A sonic boom is heard 7.0 s later, at which time the line of sight to the aircraft forms a 56° angle with respect to the horizontal. The speed of sound is 325 m/s. What is the Mach number (the ratio of the speed of the jet to the speed of sound) for the aircraft? A) 1.2 B) 1.8 C) 1.9 D) 2.1 E) 2.2
A
A machinist needs to remove a tight fitting pin of material A from a hole in a block made of material B. The machinist heats both the pin and the block to the same high temperature and removes the pin easily. What statement relates the coefficient of thermal expansion of material A to that of material B? A) Material B has a greater coefficient of expansion than does material A. B) The situation is not possible because heating block B will shrink the hole in the material as the material expands with increasing temperature. C) Material B has the same coefficient of expansion as does material A. D) Material A has a greater coefficient of expansion than does material B.
A
A pipe that is 0.46 m long and open at both ends vibrates in the second overtone with a frequency of 1150 Hz. In this situation, the distance from the center of the pipe to the nearest antinode is closest to A) 7.7 cm. B) 3.8 cm. C) 12 cm. D) 15 cm. E) zero.
A
A policeman in a stationary car measures the speed of approaching cars by means of an ultrasonic device that emits a sound with a frequency of 41.2 kHz. A car is approaching him at a speed of 33.0 m/s. The wave is reflected by the car and interferes with the emitted sound producing beats. What is the frequency of the beats? The speed of sound in air is 330 m/s. A) 9.2 kHz B) 4.1 kHz C) 4.6 kHz D) 1.2 kHz E) 8.2 kHz
A
A sample of an ideal gas is slowly compressed to one‐half its original volume with no change in temperature. What happens to the average speed of the molecules in the sample? A) It does not change. B) It becomes 4 times as great. C) It becomes 2 times as great. D) It becomes 1/2 as great. E) It becomes 1/4 as great.
A
A solid concrete wall 4.0 m by 2.4 m and 30 cm thick, with a thermal conductivity of 1.3 W/(m ·K), separates a basement at 18°C from the ground outside at 6°C. Under steady state conditions, how much heat flows through the wall in one hour? A) 1.8 MJ B) 1.8 kJ C) 500 J D) 5.0 MJ E) 5.0 kJ
A
A sound source emits 20.0 W of acoustical power spread equally in all directions. The threshold of hearing is 1.0 × 10-12 W/m2. What is the sound intensity level 30.0 m from the source? I = P/4pir^2 = 20/4*3.14*30^2 = 1.769x10^-3 Intensity level = 10dBlog(1.769x10^-3 /10^-12) = A) 92.5 dB B) 81.5 dB C) 1.77 × 10-3 dB D) 1.77 × 10-3 W E) -27.5 dB
A
A substance has a melting point of 20°C and a heat of fusion of 3.5 × 104 J/kg. The boiling point is 150°C and the heat of vaporization is 7.0 × 104 J/kg at a pressure of 1.0 atm. The specific heats for the solid, liquid, and gaseous phases are 600 J/(kg·K), 1000 J/(kg·K), and 400 J/(kg·K), respectively. The quantity of heat given up by 0.50 kg of the substance when it is cooled from 170°C to 88°C, at a pressure of 1.0 atmosphere, is closest to A) 70 kJ. B) 14 kJ. C) 21 kJ. D) 30 kJ. E) 44 kJ.
A
A substance has a melting point of 20°C and a heat of fusion of 3.9 x 104 J/kg. The boiling point is 150°C and the heat of vaporization is 7.8 × 104 J/kg at a pressure of 1.0 atm. The specific heats for the solid, liquid, and gaseous phases are 600 J/(kg·K), 1000 J/(kg·K), and 400 J/(kg·K), respectively. The quantity of heat required to raise the temperature of 3.80 kg of the substance from -6°C to 128°C, at a pressure of 1.0 atm, is closest to A) 620 kJ. B) 470 kJ. C) 560 kJ. D) 210 kJ. E) 770 kJ.
A
For a fixed amount of gas, if the absolute temperature of the gas is doubled, what happens to the pressure of the gas? A) The answer cannot be determined without volume information. B) The pressure of the gas becomes double the original pressure. C) The pressure of the gas becomes eight times the original pressure. D) The pressure of the gas becomes one half the original pressure. E) The pressure of the gas becomes four times the original pressure.
A
If we double the root‐mean‐square speed (thermal speed) of the molecules of a gas, then A) its temperature must increase by a factor of 4. B) its temperature must increase by a factor of 2. C) its temperature must increase by a factor of 2. D) its pressure must increase by a factor of 2. E) its pressure must increase by a factor of 4.
A
If we use 67 W of power to heat 148 g of water, how long will it take to raise the temperature of the water from 15°C to 25°C? The specific heat of water is 4190 J/kg•K. A) 93 s B) 5.3 s C) 22 s D) 114 H
A
The coefficient of linear expansion of aluminum is 24 × 10-6 K-1 and the coefficient of volume expansion of olive oil is 0.68 × 10-3 K-1. A novice cook, in preparation for deep-frying some potatoes, fills a 1.00-L aluminum pot to the brim and heats the oil and the pot from an initial temperature of 15°C to 190°C. To his consternation some olive oil spills over the top. How much? real expansion = apparent expansion + volume expansion of vessel 0.68*10^-3 = rapp + 3*24*10^-6 r = 608*10^?6 /K r = dV/V*dT dV = rapp*V*dT = 608e?6*1*(190-15) = A) 0.11 L B) 0.12 L C) 0.13 L D) 0.14 L E) 0.15 L
A
The hole for a bolt in a brass plate has a diameter of 1.200 cm at 20°C. What is the diameter of the hole when the plate is heated to 220°C? The coefficient of linear thermal expansion for brass is 19 × 10-6/C°. (Express your answer to 4 significant figures.) A) 1.205 cm B) 1.125 cm C) 1.195 cm D) 1.200 cm E) 1.210 cm
A
The intensity level of a "Super-Silent" power lawn mower at a distance of 1.0 m is 100 dB. You wake up one morning to find that four of your neighbors are all mowing their lawns using identical "Super-Silent" mowers. When they are each 20 m from your open bedroom window, what is the intensity level of the sound in your bedroom? You can neglect any absorption, reflection, or interference of the sound. The lowest detectable intensity is 1.0 × 10-12 W/m2. A) 80 dB B) 104 dB C) 400 dB D) 50 dB E) 40 dB
A
Two identical loudspeakers that are 5.00 m apart and face toward each other are driven in phase by the same oscillator at a frequency of 875 Hz. The speed of sound in the room is 344 m/s. If you start out standing midway between the speakers, find the shortest distance you can walk toward either speaker in order to hear a minimum of sound. A) 0.0983 m B) 0.197 m C) 0.295 m D) 0.393 m E) 0.590 m
A
Two loudspeakers placed 6.0 m apart are driven in phase by an audio oscillator whose frequency range is 2193 Hz to 2967 Hz. A point P is located 4.4 m from one loudspeaker and 3.6 m from the other. The speed of sound is 344 m/s. The frequency produced by the oscillator, for which constructive interference of sound occurs at point P, is closest to A) 2580 Hz. B) 2903 Hz. C) 2473 Hz. D) 2795 Hz. E) 2688 Hz.
A
Two motors in a factory are running at slightly different rates. One runs at 825 rpm and the other at 786 rpm. You hear the sound intensity increase and then decrease periodically due to wave interference. How much time elapses between successive maxima of the sound intensity? A) 1.5 s B) 1.4 s C) 1.7 s D) 1.8 s
A
Two stereo speakers mounted 4.52 m apart on a wall emit identical in -phase sound waves. You are standing at the opposite wall of the room at a point directly between the two speakers. You walk 2.11 m parallel to the wall, to a location where you first notice that the sound intensity drops to zero. If the wall along which you are walking is 10.7 m from the wall with the speakers, what is the wavelength of the sound waves? CAREFUL! The distance to the wall is NOT much greater than the distance between the speakers. A) 1.7 m B) 2.1 m C) 2.6 m D) 2.9 m
A
Which contains more moles of material: 80 grams of helium gas (He, having atomic weight 4.0 g/mol) or 400 grams of argon gas (Ar, having atomic weight 40 g/mol)? A) helium B) argon C) Both contain the same number of moles.
A
A cube at 100°C radiates heat at a rate of 80.0 J/s. If its surface temperature is increased to 200°C, the rate at which it will now radiate is closest to A) 160 J/s. B) 207 J/s. C) 320 J/s. D) 640 J/s. E) 1280 J/s.
B
A person pours 330 g of water at 45°C into an 855-g aluminum container with an initial temperature of 10°C. The specific heat of aluminum is 900 J/(kg·K) and that of water is 4190 J/(kg·K). What is the final temperature of the system, assuming no heat is exchanged with the surroundings? A) 28°C B) 32°C C) 31°C D) 33°C E) 35°C
B
An organ pipe open at both ends has two successive harmonics with frequencies of 210 Hz and 240 Hz. What is the length of the pipe? The speed of sound is 344 m/s in air. Fn=nV/2*L F(n+1)=(n+1)V/2*L L= meter A) 5.25 m B) 5.73 m C) 2.76 m D) 4.90 m E) 3.62 m
B
As you stand by the side of the road, a car approaches you at a constant speed, sounding its horn, and you hear a frequency of 80.0 Hz. After the car goes by, you hear a frequency of 60.0 Hz. What is the speed of the car? The speed of sound in the air is 343 m/s. A) 64.0 m/s B) 49.0 m/s C) 16.0 m/s D) 36.0 m/s E) 25.0 m/s
B
If the intensity level at distance d of one trombone is 70 dB, what is the intensity level of 76 identical trombones, all at distance d? A) 146 dB B) 89 dB C) 5320 dB D) 76 dB E) 82 dB
B
It is a well‐known fact that water has a higher specific heat than iron. Now, consider equal masses of water and iron that are initially in thermal equilibrium. The same amount of heat, 30 calories, is added to each one. Which statement is true? A) They remain in thermal equilibrium. B) They are no longer in thermal equilibrium; the iron is warmer. C) They are no longer in thermal equilibrium; the water is warmer. D) It is impossible to say without knowing the exact mass involved. E) It is impossible to say without knowing the exact specific heats.
B
One of the harmonics of a column of air open at one end and closed at the other has a frequency of 448 Hz and the next higher harmonic has a frequency of 576 Hz. What is the fundamental frequency of the air column? A) 32 Hz B) 64 Hz C) 88 Hz D) 128 Hz E) 256 Hz
B
The coefficient of volume expansion of olive oil is 0.68 × 10-3 K-1. A 1.00-L glass beaker is filled to the brim with olive oil at room temperature. The beaker is placed on a range and the temperature of the oil and beaker increases by 25 C°. As a result, 0.0167 L of olive oil spill over the top of the beaker. What is the coefficient of linear expansion of the glass? A) 1.0 × 10-6 K-1 B) 4.0 × 10-6 K-1 C) 1.0 × 10-5 K-1 D) 2.0 × 10-5 K-1 E) 3.0 × 10-5 K-1
B
Two metal rods, one silver and the other copper, are both attached to a steam chamber as shown in the figure, with a temperature of 100°C, at one end, and an ice water bath, with a temperature of 0°C, at the other. The rods are 5.0 cm long and have a square cross -section, 2.0 cm on a side. When steady state has been reached, how much heat flows through the two rods in 1.0 min? The thermal conductivity of silver is 417 W/(m·K), and that of copper is 395 W/(m ·K). No heat is exchanged between the rods and the surroundings, except at their ends. A) 20 kJ B) 39 kJ C) 47 kJ D) 49 kJ E) 11 kJ
B
Two strings of identical material and radius are stretched with the same tension with their ends fixed, but one string is 8.0 mm longer than the other. Waves on these strings propagate at 420 m/s. The fundamental frequency of the longer string is 528 Hz. What is the beat frequency when each string is vibrating at its fundamental frequency? A) 22 Hz B) 11 Hz C) 16 Hz D) 5.5 Hz E) 27 Hz
B
1.000 L of water at 20.00°C will occupy what volume if it is heated to 80.00°C? Water has a volume expansion coefficient of 210 × 10-6/C°. (Express your answer to 4 significant figures.) A) 1.600 L B) 1.326 L C) 1.013 L D) 0.9870 L E) 0.9987 L
C
A certain crying baby emits sound with an intensity of 8.0 × 10-8 W/m2. What is the intensity level due to a set of five such crying babies, all crying with the same intensity? You can neglect any absorption, reflection, or interference of the sound. The lowest detectable intensity is 1.0 × 10-12 W/m2. Sound intensity of one baby: I = 8.0*10^-8 W/m².n = 5 equally loud incoherent sound sources (babies) result in a higher level of 10 × log (5) = +7 dB compared to the case that only one source is available. Reference sound intensity Io = 10^−12 W/m² (Threshold of hearing).Get sound intensity level LI in dBLI = 10*log (I / Io) dB = 10*log (8.0*10^-8 / 10^−12) = 49 dB.The total intensity level of 5 babies is LI = 49 + 7 = A) 79 dB B) 69 dB C) 56 dB D) 49 dB E) 36 dB
C
A cylindrical bar that us well insulated around its sides connects hot and cold reservoirs and conducts heat at a rate of 10.0 J/s under steady state conditions. If all of its linear dimensions (diameter and length) are reduced by half, the rate at which it will now conduct heat between the same reservoirs is closest to A) 80.0 J/s. B) 20.0 J/s. C) 5.00 J/s. D) 2.50 J/s. E) 1.25 J/s.
C
A fixed amount of ideal gas is held in a rigid container that expands negligibly when heated. At 20°C the gas pressure is p. If we add enough heat to increase the temperature from 20°C to 40°C, the pressure will be A) impossible to determine since we do not know the number of moles of gas in the container. B) greater than 2p. C) less than 2p. D) equal to 2p. E) impossible to determine since we do not know the volume of gas in the container.
C
If the temperature of a fixed amount of an ideal gas is increased, it NECESSARILY follows that A) the pressure of the gas will increase. B) the volume of the gas will increase. C) the speed of the gas molecules will increase. D) All of the above statements are correct.
C
Two in-phase loudspeakers are some distance apart. They emit sound with a frequency of 1536 Hz. You move between the speakers, along the line joining them, at a constant speed of 2.8 m/s. What beat frequency do you observe? The speed of sound in the room is 330 m/s. A) 13 Hz B) 431 Hz C) 26 Hz D) 4.7 Hz E) 118 Hz
C
A container is filled with a mixture of helium (light molecules) and oxygen (heavy molecules) gases. A thermometer in the reads 22°C. Which gas molecules have the greater average speed? A) It is the same for both of the gases because the temperatures are the same. B) The oxygen molecules do because they are diatomic. C) The oxygen molecules do because they are more massive. D) The helium molecules do because they are less massive. E) The helium molecules do because they are monatomic
D
A heavy stone of mass m is hung from the ceiling by a thin 8.25-g wire that is 65.0 cm long. When you gently pluck the upper end of the wire, a pulse travels down the wire and returns 7.84 ms later, having reflected off the lower end. The speed of sound in the room is 344 m/s, and the stone is heavy enough to prevent the lower end of the wire from moving. If the wire is vibrating in its second overtone, what is the frequency of the sound it will produce? A) 128 Hz B) 191 Hz C) 255 Hz D) 383 Hz E) 765 Hz
D
A mole of oxygen (O2) molecules and a mole of carbon dioxide (CO2) molecules at the same temperature and pressure have A) the same average molecular speeds. B) the same number of atoms. C) different average kinetic energy per molecule. D) the same number of molecules. E) different volumes.
D
A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper; the aluminum and the copper are in thermal contact. The specific heat of aluminum is more than double that of copper. Which object experiences the greater temperature change during the time the system takes to reach thermal equilibrium? A) The copper experiences a greater temperature change. B) The aluminum experiences a greater temperature change. C) Neither; both objects experience the same magnitude temperature change. D) It is impossible to tell without knowing the masses. E) It is impossible to tell without knowing the volumes
D
If 2.0 g of water at 0.00°C is to be vaporized, how much heat must be added to it? The specific heat of water is 1.0 cal/g·K, its heat of fusion is 80 cal/g, and its heat of vaporization is 539 cal/g. Heat = m(S* del T + Lv) heat = 2 * (1*100 + 539) = Cal A) 1100 cal B) 1100 kcal C) 1200 cal D) 1300 cal E) 1500 cal
D
The average molecular kinetic energy of a gas can be determined by knowing A) only the number of molecules in the gas. B) only the volume of the gas. C) only the pressure of the gas. D) only the temperature of the gas. E) All of the above quantities must be known to determine the average molecular kinetic energy.
D
The sound level at 1.0 m from a certain talking person talking is 60 dB. You are surrounded by five such people, all 1.0 m from you and all talking equally loud at the same time. The threshold of hearing is 1.0 × 10-12 W/m2. What sound level are you being exposed to? You can neglect any absorption, reflection, or interference of the sound. The threshold of hearing is 1.0 × 10-12 W/m2. Io = 1*10^-12 W/m^2 then 60 dB = 10dB*log(I/10^-12) I/10^-12 = 10^6 I = 10^-6 due to 5 persons it was 5*10^-6 then intensity level due to 5 persons is beta' = 10 dB*log*(5*10^-6/10^-12) = A) 300 dB B) 60 dB C) 74 dB D) 67 dB E) 81 dB
D
Two harmonic sound waves reach an observer simultaneously. The observer hears the sound intensity rise and fall with a time of 0.200 s between the maximum intensity and the succeeding minimum intensity. What is the difference in frequency of the two sound waves? time period = 2 x 0.2 = 0.4 difference in frequency = f = 1/T = 1/0.4 = Hz A) 10.0 Hz B) 0.200 Hz C) 5.00 Hz D) 2.50 Hz E) 1.25 Hz
D
Under steady state conditions, a piece of wood 350 mm by 350 mm and 15 mm thick conducts heat through its thickness and loses no appreciable heat through its well-insulated sides. The rate of heat flow is measured to be 14.0 W when the temperature difference across its thickness is 28 C°. Determine the thermal conductivity of this wood. A) 9.2 × 10-4 W/(m·C°) B) 270 W/(m·C°) C) 16 W/(m·C°) D) 0.061 W/(m·C°) E) 33 W/(m·C°)
D
When a solid melts A) the temperature of the substance increases. B) the temperature of the substance decreases. C) heat energy leaves the substance. D) heat energy enters the substance.
D
You are driving along a highway at 35.0 m/s when you hear the siren of a police car approaching you from behind and you perceive the frequency as 1370 Hz. You are relieved that he is in pursuit of a different speeder when he continues past you, but now you perceive the frequency as 1330 Hz. What is the speed of the police car? The speed of sound in air is 343 m/s. A) 38.4 m/s B) 30.0 m/s C) 39.2 m/s D) 40.0 m/s E) 41.7 m/s
D
A 1.30-m long gas column that is open at one end and closed at the other end has a fundamental resonant frequency 80.0 Hz. What is the speed of sound in this gas? The formula for sound in case of pipe with one end closed is given by V=4fL V=4*80*1.3= m/s A) 104 m/s B) 61.5 m/s C) 26.0 m/s D) 246 m/s E) 416 m/s
E
A bat emits a sound at a frequency of 30.0 kHz as it approaches a wall. The bat detects beats such that the frequency of the echo is 900 Hz higher than the frequency the bat is emitting. The speed of sound in air is 340 m/s. The speed of the bat is closest to A) 20.0 m/s. B) 530 m/s. C) 10.0 m/s. D) 30.0 m/s. E) 5.02 m/s.
E
An air column, open at one end and closed at the other, is being designed so that its second lowest resonant frequency is 440 Hz. What should be the length of the column if the speed of sound in air is 340 m/s? 3v/4L = f L = 3(340)/4(440) L = 0.58 m A) 0.386 m B) 0.772 m C) 1.16 m D) 0.193 m E) 0.580 m
E
Betelgeuse is a red supergiant star in the constellation Orion. It radiates heat at the rate of 2.70 × 1030 W and has a surface temperature of 3000 K. Assuming that it is a perfect emitter, what is the radius of Betelgeuse? The Stefan-Boltzmann constant is 5.670 × 10-8 W/m2 · K4. A) 7.80 × 1010 m B) 8.70 × 1010 m C) 1.40 × 1011 m D) 1.90 × 1011 m E) 2.16 × 1011 m
E
The filament in a light bulb has a diameter of 0.050 mm and an emissivity of 1.0. The temperature of the filament is 3000°C. What should be the length of the filament so it will radiate 60 W of power? The Stefan-Boltzmann constant is 5.670 × 10-8 W/m2 · K4. A) 11 cm B) 9.4 cm C) 8.6 cm D) 7.2 cm E) 5.9 cm
E
The number of molecules in one mole of a substance A) depends on the molecular weight of the substance. B) depends on the atomic weight of the substance. C) depends on the density of the substance. D) depends on the temperature of the substance. E) is the same for all substances.
E
The sound from a single source can reach point O by two different paths. One path is 20.0 m long and the second path is 21.0 m long. The sound destructively interferes at point O. What is the minimum frequency of the source if the speed of sound is 340 m/s? A) 340 Hz B) 6800 Hz C) 520 Hz D) 680 Hz E) 170 Hz
E
What is the steady state rate of heat flow through a pane of glass that is 40.0 cm by 30.0 cm with a thickness of 4.00 mm when the outside temperature of the glass is -10.0°C and its inside temperature is 25.0°C? The thermal conductivity of glass is 0.105 W/(m·K), the specific heat of glass is 0.180 cal/(g·°C), and 1 cal = 4.190 J. A) 24.2 W B) 3.81 W C) 18.6 W D) 47.3 W E) 110 W
E
You want to insert an aluminum rod, which at 20°C has a radius of 1.000200 cm into a copper tube which has a radius of 1.000100 cm at the same temperature. You decide to put both of them in the refrigerator. At what temperature will the rod just fit if both are cooled to the same temperature? The coefficient of thermal expansion for aluminum is 2.4 × 10-5 K-1, and that of copper is 1.7 × 10-5 K-1. A) 7.8°C B) 6.3°C C) 9.2°C D) 15°C E) 5.7°C
E
