Question

all six plz (better with explaination)

25. A real (non-Carnot) heat engine, opcrating between heat reservoirs at temperatures of 650 K (hot) and 270 K (cold) performs 4.3 kJ of net work and rejects 8.0 kJ of heat in a single cycle. The thermal efliciency of this heat engine is closest to A. 0.35. B. 0.31 C. 0.28 D. 0.38 E. 0.42 26. A 2.0-kg block of aluminum at 50° is dropped into 5.0 kg of water at 20°C and the tempcrature is allowed to stabilize. What is the final temperature of the system? The heat capacity of aluminum is 910 J/K- kg, and the heat capacity of water is 4190 J/K - kg. A. 20° B. 220 C. 25 D. 50 E. None of the other answers. 27. A heat engine operating at 600 K exhausts heat into the atmosphere, which is at 300 K. What is the maximum possible efficiency this heat engine could have? A. 100% 13. 20% C.30% D. 4096 E, 50% 28. You are driving along a highway at 35.0 m/s when you hear the siren of a police car ap- proaching you from bchind and you perceive the frequency as 1310 Hz. You are relieved that he is in pursuit of a different speeder when he continues past you, but now you perceive the frequency as 1240 Hz. What is the actual frequency of the siren in the police car? The speed of sound in air is 343 m/s. A. 1300 Hz B. 1320 Hz C. 1270 Hz D. 1360 Hz E. 1370 Hz 29. Two violinists are trying to tune their instruments in an orchestra. One is producing the desired frequency of 40.0 Hz (musicians call this A above middle C). The other is producing a frequency of 118.1 Hz By what percentage should the second (out-of-tune) musician change the tension in his string to bring his instrument into tune at 440.0 Hz? A. +1.9% C. +3.7% E. +8.4% 30. The angular velocity of a 1-kg wheel 20-cm in diameter is given by the equation (t) rad/s)t (2 rad/s4)t3 what is the angular acceleration α in rad/s2 of the wheel at the end of the first 2 seconds of its motion? B. α-: 12 rad/s? C. α-24 rad/s2 D. α = 32 rad/s2 E. α 8 rad/82

Answer 1

T1=270K 76 Tz = 32.3k TW 2273 ener 7 323-T 115T 372. +19 dh Solui

hィ 12 치- 1 -1 6