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Re: [Phys-l] Marylin vos Savant again!

Hi,

Often during Tucson HOT DRY early summer, I have been driving in a car and stuck my hand out the window when it was 105F. The result was my hand got hotter, yet when bicycling home, I feel cooled by the air flow. I suspect that the explanation of this seeming contradiction is that when in the car, my sweat glands were on low. When cycling they are on overdrive. (I am dry when I get home but am soaked after a few minutes in my house with A/C. I down a quart of water in the four miles to home.) I suspect that sweat glands kick in in response to elevated core temperature.

Thanks
Roger U of AZ

===============================================================
On 8/30/2011 12:21 PM, John Denker wrote:
I can't think of any scenario where Marylin's answer makes sense.

a) If the humidity is high, the fan won't help, but then the
person won't get dehydrated, contrary to what she said.

b) If the humidity is not high, the fan helps quite a bit,
contrary to what she said. This is why people buy fans.
The amount you have to drink to keep hydrated under the
stated conditions, sitting on the porch, is not zero but
not unreasonable.

*) Maybe there is some other scenario in which what she said
makes sense, in which case her answer is only "mostly" wrong
... but I can't think of any such scenario. More importantly,
in any case, she should have /told/ us what she is talking
about. We shouldn't have to guess.

I just got through riding my bike for 30 miles. It's 105
in the shade and there's no shade. Also no breeze. On the
other hand, the humidity is 20%, so it's not hard to keep
cool, given enough to drink. My point here is that I'm a
lot cooler when I'm in motion than when I stop. A fan (or
a breeze) helps enormously under these conditions.
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