Question

please answer as many as possible

11, A water-cooled electric power plant generates 300 MW of power at efficiency of 35%. At what rate must water be circulated past the condenser if the change in water temperature is not to exceed 20 C? (The specific heat of water is 4.2 x ios J/kg°C) A) E) 14000 x 10 kg/s 7000x10 kg/s 21000 x103 kg/s B) 6000 × 103 kg/s C) D) 4000 x1OP kg/s 12. A generator operates between a hot and cold temperature of 590 C and 220 C. If the generator operates at 40% of its theoretical maximum efficiency and does work at a rate of 1200w, calculate how much heat is discharged per hour A) 18.8 MJ B) 116MJ C) 23.0MJ D) 20.9MJ E) 12.9MJ 13. Modern railway tracks consist of continuous welded-steel rails of 1000 m lengths. If the coefficient of linear expansion of steel is 14 x 10- K-1, by how much would such a rail change in length between the highest summer temperature, 43°C, and the lowest winter temperature, -35 C? A) 109 cm B) 36cm C) 327cm D) 55 cm E) 218 cm 14. The wall of a house consists of three layers: a wooden outer wall with an R factor of 1.00, a 3-in layer of fiberglass insulation with an R factor of 14.00, and a gypsum-board inner wall with an R factor of 0.36; (all R factors are in h. ft2·。F/Btu). When the temperature is 70℉ inside the house and-7"F outside, what is the rate of heat loss through an 8-ft by 15-ft section of this wall? A) 500 Btu/h B) 334Btu/h C) 1001 Btu/h D) 667 Btu/h E) 1334 Btu/h 15. A certain blackbody radiates 200 W at a temperature of 3000 K. How much power would this body radiate at 3600 K? A) 581W B) 96W C) 415W D) 664 W E) 498W 10-3 cal/(s cm C). The amount of heat conducted per minute per square centimeter through this wall is A) 33.4 cal㎝-2 mín-ı B) 7.4 cal cm-2 min-1 C) 445cal cm-2 min-1 16. The temperature gradient in a wall is 135 C/cm, and the thermal conductivity of this wall is 5.5 x nately D) 22.3 cal em-2min E) 66.8 cal cm-2 min- 17. A string of length 7m has a mass of 15g and is under a tension of 12.50 N. The speed of a transverse wave in this string is A) 168.03 m/s B) 15.28m/s C) 763.76m/s D) 76.38 m/s E) 84.01 m/s 18. The equation of a transverse wave is 0.02 m cos(6z/m-400t/s) y(x, t) where m and s are SI units. The velocity of the wave is A) 200.01 m/s B) 100.0m/s C) 66.67 m/s D) 133.34m/s E) 266.68 m/s 19. The particle displacement of a medium in which there is a simple harmonic wave is given by the equation y(z,t) (2m/x) sin[n(x/m -4t/s)], where m and s are SI units. At t6.1s the speed of a particle at 14.2m is A) 0.515m/s B) 1.03 m/s C) 6.472m/s D) 2.472m/s E) 4.702m/s

Answer 1