(c) The coefficient of performance for a freezer is 7.8. Pekali prestasi untuk penyejuk beku ialah 7.8. (i) How much heat must be extracted by the freezer to expel 2.5 kJ of heat into the reservoir? Berapa banyak haba yang harus dikeluarkan oleh penyejuk beku untuk mengeluarkan 2.5 kJ haba ke dalam takungan? (ii) If the freezer compressor uses 310 J of energy, how much heat is extracted from the reservoir?

(II) A heat engine uses a heat source at 580°C and has an ideal(Carnot) efficiency of 22%. To increase the ideal efficiencyto 42%, what must be the temperature of the heat source?

(II) 8.5 moles of an ideal monatomic gas expand adiabatically, performing 8300 J of work in the process. What is the change in temperature of the gas during this expansion?

(a) At a steam power plant, steam engines work in pairs, the heat output of the first one being the approximate heat input of the second. The operating temperatures of the first are 750°C and 440°C, and of the second 415°C and 270°C. If the heat of combustion of coal is 2.8 × 107 J/kg, at what rate must coal be burned if the plant is to put out 950 MW of power? Assume the efficiency of the engines is 65% of the ideal (Carnot) efficiency. (b) Water is used to cool the power plant. If the water temperature is allowed to increase by no more than 4.5 C°, estimate how much water must pass through the plant per hour.

(a) A freezer maintains an interior temperature inside of -22.0°C and has a coefficient of performance of 3.00. The freezer sits in a room with a temperature of 22.0°C. The freezer is able to completely convert 20.0 g of liquid water at 22.0°C to ice at -22.0°C in one minute. What input power (in watts) does the freezer require? (The specific heat of liquid water is 4.186 J/(g. °C), the specific heat of ice is 2.090 J/(g °C), and the latent heat of fusion of water is 334 J/g.) W . (b) What If? In reality, only part of the power consumption of a freezer is used to make ice. The remainder is used to maintain the temperature of the rest of the freezer. Suppose, however, that 100% of a freezer's typical power consumption of 160 W is available to make ice. The freezer has the same coefficient of performance as given above. How many grams per minute of water at 22.0°C could this freezer convert to ice at -22.0°C? g/min

(II) (a) What is the coefficient of performance of an idealheat pump that extracts heat from 6°C air outside anddeposits heat inside a house at 24°C? (b) If this heat pumpoperates on 1200 W of electrical power, what is the maximumheat it can deliver into the house each hour? see the attached problem

(I) If an ideal refrigerator keeps its contents at 2.5°C whenthe house temperature is 22°C, what is its COP?

(II) A heat pump is used to keep a house warm at 22°C. How much work is required of the pump to deliver 3100 J of heat into the house if the outdoor temperature is (a) 0°C, (b) –15°C? Assume a COP of 3.0. (c) Redo for both temperatures, assuming an ideal (Carnot) coefficient of performance COP = TH/(TH – TL).

(III) When a gas is taken from a to c along the curved path in Fig. 15–24, the work done by the gas is W = -35 J and the heat added to the gas is Q = -175 J. Along path abc, the work done by the gas is W = -56 J. (That is, 56 J of work is done on the gas.) (a) What is Q for path abc? (b) If P = P,, what is W for path cda? (c) What is Q for path cda? (d) What is Ua - U.? (e) If Ua - U. = 42 J, what is Q for path da? P b P. FIGURE 15-24 Problem 13. V