A domestic refrigerator is loaded with food and the door is closed. During a certain period the machine consumes 1 kwh of energy and the internal energy of the system drops by 5000 kj. Find the net heat transfer for the system.
Answers
Answer:
An insulated rigid vessel contains some powdered coal and air at a pressure of 10 bar and a temperature of 200 C. The coal is ignited, there results a rise in the pressure and temperature of the contents of the vessel, the final temperature is 5380 C. Taking the vessel and the contents to be the system under consideration evaluate the increase in the energy of the system. b) The insulation is now removed. A heat transfer. of 50 kJ from the system causes the temperature to fall to the initial value, 200 C. Evaluate the increase in the energy of the system during this process. c) Taking the initial energy of the system 32 kJ, write down the energy values after process (a) and after process (b). On a warm summer day, a housewife decides to beat the heat by closing the windows and doors in the kitchen and opening the refrigerator door. At first she feels cool and refreshed, but after a while the effect begins to wear off. Evaluate the situation as it relates to first law, considering the room including the refrigerator as the system.
Solution:
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Answer:
-8.6MJ
Explanation:
the work done by the system is positive 1J=W.s .So work done by refeigirator is 3600KW.s.the internal energy is given that 5000KJ,work=3600KJ
wkt,,H=U+W
therefore H=-3600-5000
=-8600KJ
=-8.6MJ