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free/or 0.5$ |
| 55703 | If a 35.0%-efficient Carnot heat engine (Fig. 22.2) is run in reverse so as to form a refrigerator (Fig. 22.5), what would be this refrigerator’s coefficient of performance? |
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| 55704 | An idealized diesel engine operates in a cycle known as the air-standard diesel cycle, shown in Figure 22.14. Fuel is sprayed into the cylinder at the point of maximum compression; B. Combustion occurs during the expansion B → C, which is modeled as an isobaric process. Show that the efficiency of an engine operating in this idealized diesel cycle is |
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| 55705 | An ideal refrigerator or ideal heat pump is equivalent to a Carnot engine running in reverse. That is, energy Q c is taken in from a cold reservoir and energy Q h is rejected to a hot reservoir.
(a) Show that the work that must be supplied to run the refrigerator or heat pump is |
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| 55706 | An ideal gas is taken through a Carnot cycle. The isothermal expansion occurs at 250°C, and the isothermal compression takes place at 50.0°C. The gas takes in 1 200 J of energy from the hot reservoir during the isothermal expansion. Find
(a) The energy expelled to the cold reservoir in each cycle and
(b) The net work done by the gas in each cycle. |
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| 55707 | An ideal gas is enclosed in a cylinder that has a movable piston on top. The piston has a mass m and an area A and is free to slide up and down, keeping the pressure of the gas constant. How much work is done on the gas as the temperature of n mol of the gas is raised from T1 to T2? |
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| 55708 | An ideal gas is enclosed in a cylinder with a movable piston on top of it. The piston has a mass of 8 000 g and an area of 5.00 cm2 and is free to slide up and down, keeping the pressure of the gas constant. How much work is done on the gas as the temperature of 0.200 mol of the gas is raised from 20.0°C to 300°C? |
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| 55709 | An ideal gas is contained in a vessel at 300 K. If the temperature is increased to 900 K, by what factor does each one of the following change?
(a) The average kinetic energy of the molecules.
(b) The rms molecular speed.
(c) The average momentum change of one molecule in a collision with a wall.
(d) The rate of collisions of molecules with walls.
(e) The pressure of the gas. |
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| 55710 | An ideal gas is carried through a thermodynamic cycle consisting of two isobaric and two isothermal processes as shown in Figure P20.69. Show that the net work done on the gas in the entire cycle is given by |
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| 55711 | An ideal gas initially at Pi, Vi, and Ti is taken through a cycle as in Figure P20.38.
(a) Find the net work done on the gas per cycle.
(b) What is the net energy added by heat to the system per cycle?
(c) Obtain a numerical value for the net work done per cycle for 1.00 mol of gas initially at 0°C. |
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| 55712 | An ideal gas initially at 300 K undergoes an isobaric expansion at 2.50 kPa. If the volume increases from 1.00 m3 to 3.00 m3 and 12.5 kJ is transferred to the gas by heat, what are (a) the change in its internal energy and
(b) Its final temperature? |
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| 55713 | An ice tray contains 500 g of liquid water at 0°C. Calculate the change in entropy of the water as it freezes slowly and completely at 0°C. |
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| 55714 | How much work is required, using an ideal Carnot refrigerator, to change 0.500 kg of tap water at 10.0°C into ice at - 20.0°C? Assume the temperature of the freezer compartment is held at -20.0°C and the refrigerator exhausts energy into a room at 20.0°C. |
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| 55715 | How much work is required to compress 5.00 mol of air at 20.0°C and 1.00 atm to one tenth of the original volume?
(a) By an isothermal process?
(b) By an adiabatic process?
(c) What is the final pressure in each of these two cases? |
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| 55716 | How much work is done on the steam when 1.00 mol of water at 100°C boils and becomes 1.00 mol of steam at 100°C at 1.00 atm pressure? Assuming the steam to behave as an ideal gas, determine the change in internal energy of the material as it vaporizes. |
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| 55717 | How much work does an ideal Carnot refrigerator require to remove 1.00 J of energy from helium at 4.00 K and reject this energy to a room-temperature (293-K) environment? |
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| 55718 | How much energy is required to change a 40.0-g ice cube from ice at -10.0°C to steam at 110°C? |
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| 55719 | A high fountain of water is located at the center of a circular pool as in Figure P1.61. Not wishing to get his feet wet, a student walks around the pool and measures its circumference to be 15.0 m. Next, the student stands at the edge of the pool and uses a protractor to gauge the angle of elevation of the top of the fountain to be 55.0°. How high is the fountain? |
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| 55720 | How fast are you personally making the entropy of the Universe increase right now? Compute an order-of-magnitude estimate, stating what quantities you take as data and the values you measure or estimate for them. |
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| 55721 | How could you increase the entropy of 1 mol of a metal that is at room temperature? How could you decrease its entropy? |
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| 55722 | A house loses energy through the exterior walls and roof at a rate of 5 000 J/s = 5.00 kW when the interior temperature is 22.0°C and the outside temperature is "5.00°C. Calculate the electric power required to maintain the interior temperature at 22.0°C for the following two cases.
(a) The electric power is used in electric resistance heaters (which convert all of the energy transferred in by electrical transmission into internal energy).
(b) What If? The electric power is used to drive an electric motor that operates the compressor of a heat pump, which has a coefficient of performance equal to 60.0% of the Carnot-cycle value |
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