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Hi Fred & All, Sept 22, 2012
Explanations of weight/mass usually resemble inconsistent confessions
obtained by torture but I guess that is ok now.
It seems logical to me that weight should be treated as a special case
of F=ma where a in this case is g and F is measured by exerting an equal and
opposite force upward to keep the mass from falling.
One could then determine the magnitude of mass as F/g and then proceed
to work out units of momentum, inertia etc from there.
But unfortunately kg has been defined (or perhaps redefined) as a unit
of mass which leads to everything being a hopeless muddle.
I would try to reform the system of units dealing with weight, mass and
distance but I am tied up this afternoon.
Yt, Dave Webster, Kentville
----- Original Message -----
From: "Fred Schueler" <bckcdb@istar.ca>
To: <naturens@chebucto.ns.ca>
Sent: Friday, September 21, 2012 9:19 PM
Subject: Re: [NatureNS] Correction; Fw: Velocity of light
> 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
>>
>>
>
>
>
> ------------------------------------------------------------
> 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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