1-Assume that the turbines at a coal-powered power plant were upgraded, resultin
ID: 1787796 • Letter: 1
Question
1-Assume that the turbines at a coal-powered power plant were upgraded, resulting in an improvement in efficiency of 3.34%. Assume that prior to the upgrade the power station had an efficiency of 35% and that the heat transfer into the engine in one day is still the same at 2.60 1014 J.
How much more electrical energy (in J/day) is produced due to the upgrade?
_____ J/day
2-Steam locomotives have an efficiency of 14.0% and operate with a hot steam temperature of 400°C. What would the maximum efficiency of this steam engine be if its cold reservoir temperature were 150°C?
______%
3-If you pour 0.0350 kg of 22.0°C water onto a 1.26 kg block of ice (which is initially at 15.0°C), what is the final temperature (in °C)? You may assume that the water cools so rapidly that effects of the surroundings are negligible.
_____ °C
4- Calculate the rate of heat conduction (in W) through a double-paned window that has a 2.50 m2 area and is made of two panes of 0.700 cm thick glass separated by a 1.00 cm air gap. The inside surface temperature is 18.0°C, while that on the outside is 13.0°C.
(Hint: There are identical temperature drops across the two glass panes. First find these and then the temperature drop across the air gap. This problem ignores the increased heat transfer in the air gap due to convection.)
_____ W
(b)
Calculate the rate of heat conduction (in W) through a 1.40 cm-thick window of the same area and with the same temperatures.
_____W
If you could answer these, that would be great. I will rate all correct answers. Thanks!
Explanation / Answer
1. W = n Qin
initially , W = 0.35 x 2.60 x 10^14
W = 0.91 x 10^14 J
finally, n = 0.35 (1.0334) = 0.362
W' = 0.94 x 10^14 J
more energy = 3.04 x 10^12 J/day ...........Ans
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