At 06:49 AM 6/30/02, "Erik Reuter" <[EMAIL PROTECTED]> wrote: >On Sun, Jun 30, 2002 at 05:52:44AM -0500, Robert Seeberger wrote: > > > Are you aware of how much heat the human body produces? > >Are you?
About 120 Watts. ((2,500 Calories/day) * (4186 Joules/Calorie) / (86,400 sec/day) = 121.1 Joules/sec, a calculation I perform on the board every time we start talking about energy in various forms, since to most people today, a "Calorie" is simply a measure of how much fatter you get by eating something rather than the amount of heat necessary to raise the temperature of one kilogram of water 1�C.) With 30-odd students all in the same room (I haven't measured it, but I doubt that the area of the classroom is > 900 ft�) along with one very-odd instructor who is spouting hot air, it does indeed get stuffy unless we can have the door open. However . . . > > It would be intolerably miserable at best on the coldest winter day. . . . 1 human/900 ft� means one human in a fair-sized room. None of the rooms in my house come anywhere close to 900 ft�. In fact, I think that would be close to half the living area of the whole house, and for many years this house housed three humans and still needed to be heated during even an Alabama winter. My grandparents' house was even smaller, and still had to be heated even when the entire family gathered in one room to open Christmas presents. (Now, on a summer day with both the computer and the TV/VCR running, it does get a tad warm here in the immediate vicinity . . . ) >Homework problem: look up the power per square meter of sunlight on the >earth's surface, and compare to the power produced by 1 human per 900 sq >ft. Comment on the absurdity of the above statement. The first figure is called the "solar constant" (actually, this is measured above the atmosphere): 1.37 kW/m�. 1 m = 3.28 feet, so 1 m� = 10.76 ft�, so 900 ft� = 83.6 m�, thus the power of the sunlight falling on 900 ft� of Earth is (1.37 kW/m�) * (83.6 m�) = 114.6 kW, or nearly 1,000 times the power in the form of heat given off by a person. -- Ronn! :) Ronn Blankenship Instructor of Astronomy/Planetary Science University of Montevallo Montevallo, AL Disclaimer: Unless specifically stated otherwise, any opinions contained herein are the personal opinions of the author and do not represent the official position of the University of Montevallo.
