Groups > sci.physics.relativity > #479684

Re: the famous formula

From	Thomas Heger <ttt_heg@web.de>
Newsgroups	sci.physics.relativity
Subject	Re: the famous formula
Date	2018-12-12 16:32 +0100
Message-ID	<g7co0oFbh39U1@mid.individual.net> (permalink)
References	(11 earlier) <puk4et$1kui$3@gioia.aioe.org> <g77moqF8191U1@mid.individual.net> <pummhj$vf2$2@gioia.aioe.org> <g7a3hoFoc5dU1@mid.individual.net> <puovcb$1mbf$1@gioia.aioe.org>

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Am 11.12.2018 um 19:24 schrieb Odd Bodkin:

>>>>>>
>>>>>> We have a similar problem with 'speed' and 'velocity'.
>>>>>>
>>>>>> Both have units like m/s , but one is a vector quantity (velocity) and
>>>>>> one is not (speed).
>>>>>>
>>>>>> Speed is the magnitude of velocity.
>>>>>>
>>>>>> https://examples.yourdictionary.com/examples-vector-scalar-quantity-physics.html
>>>>>>
>>>>>>> The acting force has direction.
>>>>>>> The path along which the force is acting has direction as well
>>>>>>> But the work as integral of scalar product of these 2 vectors is a
>>>>>>> scalar, without direction.
>>>>>>
>>>>>> work is NOT 'forth times path'
>>>>>>
>>>>>> but ' force times distance'.
>>>>>
>>>>> No, it is not that either. It is the integral of the scalar product between
>>>>> two vectors, the force and the differential displacement.
>>>>
>>>>
>>>> 'Work' is the name of a quantity in physics.
>>>
>>> As is velocity.
>>>
>>>>
>>>> It relates to the real world, hence is not a product of either one or
>>>> two vectors.
>>>
>>> I disagree. There are LOTS of real world quantities that are related in
>>> some way to other real world quantities. Velocity (a vector) is related to
>>> differential displacement and differential time. Momentum is related to
>>> mass and velocity.
>>
>> This is correct. But I had something against this statement:
>>
>> ".. It is the integral of the scalar product between two vectors..."
>>
>> I said: no, it is not, since a vector is a mathematical construct.
> 
> I disagree. A vector is a way to characterize a physical quantity. Velocity
> is a vector, momentum is a vector, force is a vector. All of those are
> real.

There is still a difference between 'vector' and 'physical quantity 
characterized by a vector'.

A vector is a mathematical construct, while quantities have units and a 
physical meaning.

You may characterize that quantity by an appropriate vector, but this 
does not make a vector a quantity.


>>
>> A number is also a mathematical construct. And you cannot multiply two
>> brainchilds and hope to get something real.
>>
>>
>> First statement: a quantity in physics (work) is defined as being the
>> product of one quantity (force)and some sort of length.
> 
> “the product” is too vague. Given that the two things you are multiplying
> are vectors, you have to be precise about what you mean by “product”. In
> this case “product” means scalar- or dot-product.


I was trying to show, that the product of a force and a path is not the 
right idea.

You are correct, since it is always done that way.

But it is wrong, in my opinion. So let me tell you, why work should be a 
vectorial quantity:


Force is a quantity (represented by a vector) with a direction (in space).

This vector contains enough information about the direction.

A path is actually a construct composed out of points in Euclidean 
space, which the object in question reaches at certain points in time.

First problem: the points are unimportant and do not belong into the 
calculation.

IOW: if you lift a heavy stone by one meter, the work should be equal, 
if you lift the same stone a little bit later at a different position 
(same gravity assumed).

So the location does not belong into the equation and also time 
(absolute time) does not belong there neither.

If we kick that out of the equation, we have got left 'distance' (in the 
direction of the movement), which is something we need.

This distance is a scalar.

If we multiply the scalar value of distance with a vector for force, 
then we get a good and satisfying result.


The benefit is, that the quantity would match to the usual understanding 
of the term 'work'.

It is also matched by a counterpart, similar to Newton's actio equals 
reactio.

The work is then done by the active part (in case of the stone: by you) 
and balanced by the passive part (the stone).


If work is a scalar quantity, you cannot easily do this,

Instead it would require to invent something like 'working stuff'.

But work is not a substance, but an activity (done by e.g. material 
objects).


...


TH

Thread

the famous formula RichD <r_delaney2001@yahoo.com> - 2018-12-06 10:49 -0800
  Re: the famous formula pnalsing@gmail.com - 2018-12-06 11:30 -0800
  Re: the famous formula dlzc <dlzc1@cox.net> - 2018-12-06 11:43 -0800
    Re: the famous formula RichD <r_delaney2001@yahoo.com> - 2018-12-07 10:15 -0800
      Re: the famous formula dlzc <dlzc1@cox.net> - 2018-12-07 11:13 -0800
        Re: the famous formula RichD <r_delaney2001@yahoo.com> - 2018-12-09 00:02 -0800
          Re: the famous formula dlzc <dlzc1@cox.net> - 2018-12-09 15:23 -0800
            Re: the famous formula Libor Striz <poutnik@privacy.net> - 2018-12-10 09:54 +0100
              Re: the famous formula dlzc <dlzc1@cox.net> - 2018-12-10 05:43 -0800
                Re: the famous formula Tom Roberts <tjroberts137@sbcglobal.net> - 2018-12-12 11:08 -0600
                Re: the famous formula dlzc <dlzc1@cox.net> - 2018-12-12 09:35 -0800
                Re: the famous formula Rich Carpenter <lcug@kigcohc.pa> - 2018-12-12 19:20 +0000
                Re: the famous formula Tom Roberts <tjroberts137@sbcglobal.net> - 2018-12-12 19:28 -0600
                Re: the famous formula Scott Richman <sunn@idhnonow.iv> - 2018-12-13 16:13 +0000
                Re: the famous formula "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2018-12-14 04:56 -0800
                Re: the famous formula "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2018-12-14 05:23 -0800
                Re: the famous formula RichD <r_delaney2001@yahoo.com> - 2018-12-19 13:06 -0800
                Re: the famous formula Tom Roberts <tjroberts137@sbcglobal.net> - 2018-12-19 20:32 -0600
                Re: the famous formula RichD <r_delaney2001@yahoo.com> - 2018-12-27 13:40 -0800
        Re: the famous formula Tom Roberts <tjroberts137@sbcglobal.net> - 2018-12-12 10:28 -0600
          Re: the famous formula dlzc <dlzc1@cox.net> - 2018-12-12 09:12 -0800
            Re: the famous formula Tom Roberts <tjroberts137@sbcglobal.net> - 2018-12-14 12:21 -0600
    Re: the famous formula "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2019-01-06 09:20 -0800
      Re: the famous formula "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2019-01-06 09:37 -0800
  Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-06 20:50 +0100
    Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-06 22:47 +0100
      Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-07 12:06 +0100
        Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-07 16:15 +0100
          Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-08 14:18 +0100
            Re: the famous formula Odd Bodkin <bodkinodd@gmail.com> - 2018-12-08 13:43 +0000
              Re: the famous formula "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2018-12-08 06:01 -0800
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-08 18:18 +0100
                Re: the famous formula Libor Striz <poutnik4REMOVEnntp@CAPITALSgmail.com.INVALID> - 2018-12-08 19:26 +0100
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-09 19:35 +0100
                Re: the famous formula Libor Striz <poutnik4REMOVEnntp@CAPITALSgmail.com.INVALID> - 2018-12-09 20:24 +0100
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-10 18:48 +0100
                Re: the famous formula Rich Carpenter <lcug@kigcohc.pa> - 2018-12-10 19:37 +0000
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-10 22:27 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-10 22:35 +0100
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-12 16:45 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-13 17:21 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-09 19:03 +0100
                Re: the famous formula Libor Striz <poutnik4REMOVEnntp@CAPITALSgmail.com.INVALID> - 2018-12-09 20:37 +0100
                Re: the famous formula Odd Bodkin <bodkinodd@gmail.com> - 2018-12-09 22:20 +0000
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-10 18:40 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-10 21:59 +0100
                Re: the famous formula "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-12-18 05:33 -0800
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-22 14:51 +0100
                Re: the famous formula "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-12-22 15:30 -0800
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-23 01:34 +0100
                Re: the famous formula Odd Bodkin <bodkinodd@gmail.com> - 2018-12-10 21:41 +0000
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-11 16:31 +0100
                Re: the famous formula Odd Bodkin <bodkinodd@gmail.com> - 2018-12-11 18:24 +0000
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-12 16:32 +0100
                Re: the famous formula Odd Bodkin <bodkinodd@gmail.com> - 2018-12-12 16:27 +0000
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-14 15:13 +0100
                Re: the famous formula Odd Bodkin <bodkinodd@gmail.com> - 2018-12-14 14:28 +0000
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-15 13:35 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-15 13:52 +0100
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-15 19:50 +0100
                Re: the famous formula Odd Bodkin <bodkinodd@gmail.com> - 2018-12-15 20:33 +0000
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-17 11:13 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-18 04:45 +0100
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-18 18:50 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-21 22:48 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-15 22:02 +0100
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-17 11:01 +0100
                Re: the famous formula Odd Bodkin <bodkinodd@gmail.com> - 2018-12-17 15:28 +0000
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-18 18:42 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2019-01-06 18:45 +0100
                Re: the famous formula Steve BH <sbharris@gmail.com> - 2019-01-01 16:54 -0800
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2019-01-06 17:17 +0100
                Re: the famous formula "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2019-01-06 08:35 -0800
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2019-01-07 14:56 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2019-01-06 18:47 +0100
                Re: the famous formula Odd Bodkin <bodkinodd@gmail.com> - 2018-12-15 12:55 +0000
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-13 23:14 +0100
                [OT] Work (was: the famous formula) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-11 21:56 +0100
                Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-08 20:14 +0100
            Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-09 19:22 +0100
        Re: the famous formula Libor Striz <poutnik4REMOVEnntp@CAPITALSgmail.com.INVALID> - 2018-12-07 17:57 +0100
          Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-08 14:03 +0100
            Re: the famous formula Gary Harnagel <hitlong@yahoo.com> - 2018-12-08 05:29 -0800
              Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-08 18:43 +0100
                [OT] Work (was: the famous formula) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-08 21:53 +0100
                Re: [OT] Work Thomas Heger <ttt_heg@web.de> - 2018-12-09 19:08 +0100
                Re: [OT] Work Libor Striz <poutnik4REMOVEnntp@CAPITALSgmail.com.INVALID> - 2018-12-09 19:31 +0100
                Re: [OT] Work Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-09 18:58 +0100
                Re: [OT] Work Thomas Heger <ttt_heg@web.de> - 2018-12-10 18:52 +0100
                Re: [OT] Work Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-10 22:28 +0100
                Re: [OT] Work Thomas Heger <ttt_heg@web.de> - 2018-12-11 16:36 +0100
                Re: [OT] Work Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-11 20:24 +0100
                Re: the famous formula Gary Harnagel <hitlong@yahoo.com> - 2018-12-08 14:02 -0800
            Re: the famous formula Libor Striz <poutnik4REMOVEnntp@CAPITALSgmail.com.INVALID> - 2018-12-08 16:56 +0100
              Re: the famous formula Ejí Utorka <edew@aewedoc.cl> - 2018-12-08 16:05 +0000
                Re: the famous formula Thomas Heger <ttt_heg@web.de> - 2018-12-08 18:35 +0100
                Re: the famous formula Ejí Utorka <edew@aewedoc.cl> - 2018-12-08 17:58 +0000
                Re: the famous formula Libor Striz <poutnik4REMOVEnntp@CAPITALSgmail.com.INVALID> - 2018-12-08 19:34 +0100
                Re: the famous formula Ejí Utorka <edew@aewedoc.cl> - 2018-12-08 18:54 +0000
          Re: the famous formula Ejí Utorka <edew@aewedoc.cl> - 2018-12-08 16:09 +0000
  Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-06 22:16 +0100
    Re: the famous formula Steve BH <sbharris@gmail.com> - 2019-01-01 18:15 -0800
      Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2019-01-02 22:10 +0100
  Re: the famous formula Odd Bodkin <bodkinodd@gmail.com> - 2018-12-07 16:07 +0000
    Re: the famous formula Steve BH <sbharris@gmail.com> - 2019-01-01 17:22 -0800
  Re: the famous formula Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-12-07 22:47 +0100
  Re: the famous formula "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-12-09 15:06 -0800
    Re: the famous formula benj <benj.fake@gmail.com> - 2018-12-12 13:44 -0500

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