the efficiency to 46%, what should the value of Ȗ be?
(a)
(b)9.4 In an internal combustion engine, the air-fuel mixture at the end of the ignition phase has volume 7.34×10í^4 m^3 and pressure
3.12×10^6 Pa. The air-fuel mixture expands adiabatically, pushing the piston out, to a volume of 2.82×10í^3 m^3. Assume the air-fuel mixture behaves like an ideal gas. If Ȗ = 1.42 for the air-fuel mixture, what is the final pressure after the expansion?
PaSection 10 - Heat pumps
10.1 A Carnot engine operated "in reverse" as a heat pump achieves the maximum coefficient of performance. A Carnot heat
pump operates to warm a house, where the outside temperature is 12°C and the inside temperature is 31°C. (a) What is its
COP? (b) How much work must be done on the heat pump for it to deliver 1400 J of heat energy to the interior of the house?
(a)
(b) J10.2 A heat pump on a house operates with a COP that is 35% of the theoretical maximum, between exterior and interior
temperatures of í12°C and 34°C. How much work must be done on the heat engine to supply 2200 J of heat to the interior of
the house?
J
10.3 A refrigerator operates much like a heat pump, but the desired goal of a refrigerator is to transfer heat from the cold reservoir
as efficiently as possible. For this reason, the coefficient of performance of a refrigerator is measured as Qc/W. A typical
commercial refrigerator has a coefficient of performance of about 5.5. Assume such a refrigerator is used by a market to make
ice cubes from 2.3 kg of liquid water, starting at 0°C. (a) How much work is done on the refrigerator to freeze this water into
ice? (The latent heat of fusion for the water is 3.34×10^5 J/kg.) (b) Suppose water costs 0.56 cents per kg, and energy costs 10
cents per kWh. If the market charges 99 cents for 2.3 kg of ice, what is its maximum profit on the ice? Express your answer to
the nearest cent.
(a) J
(b) cents
Section 12 - Interactive summary problem: efficiency of an automobile engine
12.1 Use the information given in the interactive problem in this section to calculate the correct amount of gasoline. Test your
answer using the simulation.
L