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| 55783 | Discuss the entropy changes that occur when you
(a) Bake a loaf of bread and
(b) Consume the bread. |
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| 55784 | Discuss the change in entropy of a gas that expands (a) at constant temperature and (b) adiabatically. |
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| 55785 | A diatomic ideal gas (y = 1.40) confined to a cylinder is put through a closed cycle. Initially the gas is at Pi, Vi, and Ti. First, its pressure is tripled under constant volume. It then expands adiabatically to its original pressure and finally is compressed isobarically to its original volume.
(a) Draw a PV diagram of this cycle.
(b) Determine the volume at the end of the adiabatic expansion. Find
(c) The temperature of the gas at the start of the adiabatic expansion and
(d) The temperature at the end of the cycle.
(e) What was the net work done on the gas for this cycle? |
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| 55786 | Determine the number of grams in a mole of the following gases: (a) Hydrogen (b) Helium (c) Carbon monoxide. |
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| 55787 | A daring ranch hand sitting on a tree limb wishes to drop vertically onto a horse galloping under the tree. The constant speed of the horse is 10.0 m/s, and the distance from the limb to the level of the saddle is 3.00 m. (a) What must be the horizontal distance between the saddle and limb when the ranch hand makes his move? (b) How long is he in the air? |
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| 55788 | Dalton’s law of partial pressures states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of gases making up the mixture. Give a convincing argument for this law based on the kinetic theory of gases. |
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| 55789 | A cylinder is closed by a piston connected to a spring of constant 2.00 X 103 N/m (see Fig. P19.50). with the spring relaxed, the cylinder is filled with 5.00 L of gas at a pressure of 1.00 atm and a temperature of 20.0°C. (a) If the piston has a cross-sectional area of 0.010 0 m2 and negligible mass, how high will it rise when the temperature is raised to 250°C? (b) What is the pressure of the gas at 250°C? |
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| 55790 | A cylinder is closed at both ends and has insulating walls. It is divided into two compartments by a perfectly insulating partition that is perpendicular to the axis of the cylinder. Each compartment contains 1.00 mol of oxygen, which behaves as an ideal gas with y = 7/5. Initially the two compartments have equal volumes, and their temperatures are 550 K and 250 K. The partition is then allowed to move slowly until the pressures on its two sides are equal. Find the final temperatures in the two compartments. You may use the result of Problem 53. |
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| 55791 | A cylinder that has a 40.0-cm radius and is 50.0 cm deep is filled with air at 20.0°C and 1.00 atm (Fig. P19.68a). A 20.0-kg piston is now lowered into the cylinder, compressing the air trapped inside (Fig. P19.68b). finally a 75.0-kg man stands on the piston, further compressing the air, which remains at 20°C (Fig. P19.68c) (a) How far down ("h) does the piston move when the man steps onto it? (b) To what temperature should the gas be heated to raise the piston and man back to hi? |
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| 55792 | A cylinder contains a mixture of helium and argon gas in equilibrium at 150°C.
(a) What is the average kinetic energy for each type of gas molecule?
(b) What is the root-mean-square speed of each type of molecule? |
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| 55793 | A cylinder containing n mol of an ideal gas undergoes an adiabatic process.
(a) Starting with the expression W = - fPdV and using the condition PVy = constant, show that the work done on the gas is |
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| 55794 | A cube 10.0 cm on each edge contains air (with equivalent molar mass 28.9 g/mol) at atmospheric pressure and temperature 300 K. Find (a) The mass of the gas, (b) its weight, and (c) The force it exerts on each face of the cube. (d) Comment on the physical reason why such a small sample can exert such a great force. |
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| 55795 | A copper wire and a lead wire are joined together, end to end. The compound wire has an effective coefficient of linear expansion of 20.0 X 10-6 (°C)-1. What fraction of the length of the compound wire is copper? |
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| 55796 | A copper telephone wire has essentially no sag between poles 35.0 m apart on a winter day when the temperature is - 20.0°C. How much longer is the wire on a summer day when TC # 35.0°C? |
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| 55797 | A copper ring (with mass of 25.0 g, coefficient of linear expansion of 1.70 X 10-5 (°C)-1, and specific heat of 9.24 X 10-2 cal/g °C) has a diameter of 5.00 cm at its temperature of 15.0°C. A spherical aluminum shell (with mass 10.9 g, coefficient of linear expansion 2.40 X 10-5 (°C)-1, and specific heat 0.215 cal/g °C) has a diameter of 5.01 cm at a temperature higher than 15.0°C. The sphere is placed on top of the horizontal ring, and the two are allowed to come to thermal equilibrium without any exchange of energy with the surroundings. As soon as the sphere and ring reach thermal equilibrium, the sphere barely falls through the ring. Find (a) the equilibrium temperature, and (b) the initial temperature of the sphere. |
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| 55798 | A cooking vessel on a slow burner contains 10.0 kg of water and an unknown mass of ice in equilibrium at 0°C at time t = 0. The temperature of the mixture is measured at various times, and the result is plotted in Figure P20.65. During the first 50.0 min, the mixture remains at 0°C. From 50.0 min to 60.0 min, the temperature increases to 2.00°C. Ignoring the heat capacity of the vessel, determine the initial mass of ice. |
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| 55799 | Convert the following to equivalent temperatures on the Celsius and Kelvin scales: (a) The normal human body temperature, 98.6°F; (b) The air temperature on a cold day, -5.00°F. |
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| 55800 | Continue the analysis of Problem 60 in Chapter 19. Following a collision between a large spacecraft and an asteroid, a copper disk of radius 28.0 m and thickness 1.20 m, at a temperature of 850°C, is floating in space, rotating about its axis with an angular speed of 25.0 rad/s. As the disk radiates infra red light, its temperature falls to 20.0°C. No external torque acts on the disk.
(a) Find the change in kinetic energy of the disk.
(b) Find the change in internal energy of the disk. (b) Find the amount of energy it radiates. |
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| 55801 | A container has a mixture of two gases: n1 mol of gas 1 having molar specific heat C1 and n2 mol of gas 2 of molar specific heat C2. (a) Find the molar specific heat of the mixture. (b) What If? What is the molar specific heat if the mixture has m gases in the amounts n1, n2, n3, . . . , nm, with molar specific heats C1, C2, C3, . . . , Cm, respectively? |
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| 55802 | A constant-volume gas thermometer is calibrated in dry ice (that is, carbon dioxide in the solid state, which has a temperature of - 80.0°C) and in boiling ethyl alcohol (78.0°C). The two pressures are 0.900 atm and 1.635 atm. (a) What Celsius value of absolute zero does the calibration yield? What is the pressure at (b) The freezing point of water and (c) The boiling point of water? |
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