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Re: Is This Correct?

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Poutnik <Poutnik4NNTP@gmail.com> wrote:
> On 08/26/2015 04:59 PM, hdblenner@gmail.com wrote:
>> On Tuesday, August 25, 2015 at 7:52:48 AM UTC-4, Poutnik wrote:
>>> why not use few formulas, instead of msny words, and SI units, that I
>>> hoped are used in imperial regions at least withing scientific community ?
>>> (162/7000 ) pounds  * 800 feet/s = linear momentum cca 18.5 pound x feet/s
>>> Where did you find multiple errors ?
>>> If the bullet is trapped by e.g. a block
>>> used to determine the bullet speed,
>>> the block gains initial momentum
>>> 18.5 pound x feet/s
>> The weight, w, of an object equals its mass, m,
>> multiplied by the acceleration of gravity, g.
>> This result follows from the law of motion, f = m a,
>> where the acceleration, a, is the acceleration of gravity, g,
>> and the force, f, equals the weight.
> Sure, this is obvious.
>> So a proper calculation of momentum would have divided the weight
>> by the acceleration of gravity and multiplied this quotient by the speed.
> Why, if mass is already known ?
> BTW, mass of objects of vey big or small mass
> is not detemined by weighing.
>> In this case the dimensions of the momentum
> Dimension of momentum is still kg m/s, resp. pound . foot/s
>> become [ pound / ( foot per second squared) ] foot per second = pound second,
>> which is a proper unit for the action of momentum.
> Weight as force and mass have different dimension,
> so pound cannot be used for both.
> Weight of mass of 1 pound on the Moon definitely is not 1 pound.
> Guess why.



Sounds like yet another case of confusion caused by using
the same word "pound" for "pound mass" as well as "pound force".

In SI, of course, N is for force and kg is for mass.

While there is that 9.8 factor converting weight in N to mass in kg there 
is no such factor converting 1 lb force to 1 lb mass because the 32 ft/s2
is "built in" to the defn of lb force.

But  there will be no convincing anyone of this if some kind of bar bet
is involved.

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Thread

Is This Correct? hdblenner@gmail.com - 2015-08-25 03:48 -0700
  Re: Is This Correct? Poutnik <Poutnik4NNTP@gmail.com> - 2015-08-25 13:52 +0200
    Re: Is This Correct? hdblenner@gmail.com - 2015-08-26 07:59 -0700
      Re: Is This Correct? Poutnik <Poutnik4NNTP@gmail.com> - 2015-08-26 17:23 +0200
        Re: Is This Correct? R Kym Horsell <kym@kymhorsell.com> - 2015-08-26 15:45 +0000
          Re: Is This Correct? Sam Wormley <swormley1@gmail.com> - 2015-08-26 11:23 -0500
      Re: Is This Correct? Odd Bodkin <bodkinodd@gmail.com> - 2015-08-26 11:28 -0500
        Re: Is This Correct? Poutnik <poutnik4nntp@gmail.com> - 2015-08-26 20:27 +0200
      Re: Is This Correct? "nuny@bid.nes" <Alien8752@gmail.com> - 2015-08-26 10:20 -0700

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