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Unformatted text preview: of heat transfer during this process? A) 20 W B) 18 W C) 12 W D) 10 W 7. The air contained in a room loses heat to the surroundings at a rate of 50 kJ/min while work is supplied to the room by computer, TV, and lights at a rate of 1.2 kW. What is the net amount of energy change of the air in the room during a 30min period? A) 0.36 kJ B) 70 kJ C) 660 kJ D) 1100 kJ 8. A 40kg rock is dropped from an elevation of 10 m. What is the velocity of the rock when it is 5m from the ground? A) 2.0 m/s B) 3.9 m/s C) 7.0 m/s D) 9.9 m/s 9. A car engine produces an average of 25 kW of power in a period of 10min during which 1.25 kg of gasoline is consumed. If the heating value of gasoline is 43,000 kJ/kg, the efficiency of this engine during this operation is A) 24% B) 28% C) 32% D) 36% 10. Which one of the equations below serves to define work? A) B) C) D)...
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 Spring '09
 Staff
 Energy, Mass Transfer, Heat Transfer, 25 kW, 18 kJ, 40kg, 30min, 501 kJ

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