Stupid Question ™
Aug. 5, 1999
By John Ruch
Q: If normal body temperature is 98.6 degrees, why is an air temperature of 95 degrees uncomfortable?
—Diana, Joe and Greg
A: Your body has to do a lot of work to maintain its temperature. It’s basically an engine, chemically burning food and using the energy to do various forms for work.
All engines are highly inefficient, due to friction and other factors. The wasted energy takes the form of heat. If it isn’t dissipated, the engine—your body, in this case—will overheat and begin to disintegrate. (This is why your car engine needs a radiator.)
Heat will flow spontaneously from a hotter area to a cooler one; likewise, without outside influence, heat will not flow from a hot area to an even hotter one. (We’ve enshrined these physical facts as the second law of thermodynamics.) Therefore, your body can get rid of its excess heat only by dumping it into cooler air.
The rate of heat loss depends on how much cooler the air is. Air at 95 degrees just isn’t much cooler than your body. It absorbs little body heat and does it very slowly, leaving you hot and uncomfortable.
The perfect air temperature—and thus the most comfortable—is one that will draw off your excess heat at the exact rate at which you produce it. This temperature occurs in a range known as the “thermoneutral zone.”
For a naked human, the thermoneutral zone is 82 to 86 degrees. For those of us who wear more than fig leaves, the thermoneutral zone is 72 to 78 degrees.
These are zones rather than exact temperatures because, according to Dr. Harrison Weed of the Ohio State University Medical Center, body temperature varies somewhat depending on individual metabolism, sex, body weight, activity level and even time of day.
Humidity, wind, precipitation and choice of clothing all also affect your heat loss; sunlight intensity, ground surface and altitude all affect your heat gain.
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An update on the June 10 column about why US and Canadian coins look similar: We noted the two currencies used to be identical in value at a time when face value equaled the amount of precious metal in the coin; therefore, coins of the same face value would be the same size.
Columbus Dispatch coin columnist George Stebinsky said that’s only part of the story. He said that Canadian coins contained less silver than US coins. He theorizes that Canada did this on purpose to prevent US coins from circulating in Canada and vice-versa.
He cites the economics principle of “Gresham’s law”: when two currencies have the same face value but different intrinsic value (e.g., one contains less silver), the chintzier one will be used to pay debts while the more valuable one will be hoarded.
Thus, low-silver Canadian coins would remain in circulation in Canada, while US coins would be hoarded until they were out of circulation. In the US, nobody would want to import the low-silver Canadian coins in the first place. This way Canada would have all the benefits of a strong dollar-based native currency at a fraction of the cost in silver.