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Quoting David & Alison Webster <dwebster@glinx.com>:
> I just dug out my 1st yr Physics (Weber, White & Manning, 1952) and
> they consistently refer to 'speed of light' as opposed to 'velocity
> of light'. Four other sources (1941, 1948, ~1965 &1962) have velocity.
* indeed, it would be ineffective to purge society, or even
literature, of all who misuse speed/velocity or weight/mass. Or, to
bring it closer to natural history, all who refer to nonhemipterans as
"bugs."
fred.
===============================================
> ----- Original Message ----- From: "David & Alison Webster"
> <dwebster@glinx.com>
> To: <NatureNS@chebucto.ns.ca>
> Sent: Friday, September 21, 2012 7:44 PM
> Subject: Velocity of light
>
>
>> Dear All, Sept 21, 2012
>> The recent discussion about transmission of electricity, reading
>> of HEAT and reading some of Energy... brings to the forefront a
>> question that has nagged me for decades. Perhaps someone can clarify.
>>
>> In the typical elementary physics text we are told that velocity
>> is a vector quantity, and to quote one text "velocity... may be
>> defined as the rate of change of position in a given direction".
>> But "In cases where the direction of motion does not require to be
>> considered , the term speed is employed to express the rate of
>> travelling."
>>
>> Based on the above I would think that the rate of movement of
>> light should be called speed, i.e. speed of light but I think it is
>> always called velocity.
>> For example, if light from the sun is reflected from two 45o
>> mirrors then a beam of light could be directed from the earth back
>> to the sun and, the velocity would then be minus 3 x 10^10 cm/sec.
>> Or if variously scattered or reflected then the velocity, relative
>> to the initial sun to earth direction, would always be less than 3
>> X 10^10 and after several reflections might be zero.
>>
>> Is there some good reason why the speed of light is termed
>> velocity of light ? Or is it called velocity because the textbook
>> authors forget what they said in chapter one by the time they write
>> chaper eleven ? (And they all copy from each other)
>> Yt, Dave Webster, Kentville
>
>
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Frederick W. Schueler & Aleta Karstad
Bishops Mills Natural History Centre - http://pinicola.ca/bmnhc.htm
Mudpuppy Night in Oxford Mills - http://pinicola.ca/mudpup1.htm
Daily Paintings - http://karstaddailypaintings.blogspot.com/
South Nation Basin Art & Science Book
http://pinicola.ca/books/SNR_book.htm
RR#2 Bishops Mills, Ontario, Canada K0G 1T0
presently in Cochrane - 49.06274N 81.02415W -
on the great Ontario Claybelt
(613)299-3107 <bckcdb at istar.ca> http://pinicola.ca/
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