Re: Viewing the spokes

From	jimp@specsol.spam.sux.com
Newsgroups	sci.physics
Subject	Re: Viewing the spokes
Date	2016-09-16 00:50 +0000
Organization	A noiseless patient Spider
Message-ID	<j7srad-4qo.ln1@mail.specsol.com> (permalink)
References	(4 earlier) <57d7567e$0$62107$b1db1813$2411a48f@news.astraweb.com> <b5edb112-90c0-4170-b32d-92ff0f562b04@googlegroups.com> <57d8ad7a$0$43782$c3e8da3$5e5e430d@news.astraweb.com> <kp2nad-u39.ln1@mail.specsol.com> <57db175c$0$31348$c3e8da3$dd9697d2@news.astraweb.com>

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benj <benj@nobody.net> wrote:
> On 9/14/2016 1:11 AM, jimp@specsol.spam.sux.com wrote:
>> benj <benj@nobody.net> wrote:
>>> On 9/13/2016 8:14 PM, nuny@bid.nes wrote:
>>>> On Monday, September 12, 2016 at 6:29:36 PM UTC-7, benj wrote:
>>>>> On 9/9/2016 10:43 PM, nuny@bid.nes wrote:
>>>>>> On Friday, September 9, 2016 at 2:51:31 PM UTC-7, benj wrote:
>>>>>>> On 9/9/2016 12:08 PM, nuny@bid.nes wrote:
>>>>>>>> On Monday, August 29, 2016 at 10:08:25 AM UTC-7, Sergio
>>>>>>>> wrote:
>>>>>>>>> Viewing the spokes
>>>>>>>>>
>>>>>>>>> A wheel with spokes rolls on the ground. A stationary
>>>>>>>>> camera takes a picture of the wheel. Due to the nonzero
>>>>>>>>> exposure time of the camera, the spokes will generally
>>>>>>>>> appear blurred. At what location(s) in the picture does
>>>>>>>>> (do) the spoke(s) not appear blurred?
>>>>>>>>
>>>>>>>>> answer,
>>>>>>>>>
>>>>>>>>> The contact point on the ground does not look blurred,
>>>>>>>>> because it is instantaneously at rest.
>>>>>>>>
>>>>>>>> There is no "instantaneous". The wheel *moves* while the
>>>>>>>> shutter is open, hence the contact patch will move, hence the
>>>>>>>> lowermost spokes will be blurred.
>>>>>>>>
>>>>>>>> Now, if you want to talk about which spokes will be *least*
>>>>>>>> blurred...
>>>>>>>>
>>>>>>> Actually, Mark, only the point of the wheel touching the ground
>>>>>>> which would be the rim is at rest.
>>>>>>
>>>>>> Actually, no, because the shutter can't open *and close*
>>>>>> "instantaneously".
>>>>>>
>>>>>> The contact patch *moves* while the shutter is open.
>>>>>>
>>>>> No it does not.
>>>>
>>>> Yes, it does.  "Contact patch" is that part of the wheel that's in
>>>> contact with the ground. When the wheel isn't moving, neither is the
>>>> contact patch. When the wheel *is* moving, so is the contact patch.
>>>> It has to or the wheel isn't rolling. That's what "moves" means when
>>>> applied to rolling wheels.
>>>>
>>>>> The points on the ground actually rise from the ground
>>>>
>>>> And while they're actually rising, they're actually blurring because
>>>> while they're actually moving the shutter is actually open.
>>>>
>>>>> before moving on so all the contact points are stationary.
>>>>
>>>> There *is no stationary* while the wheel is moving. Each subsequent
>>>> point on the rim that comes in contact with the ground *while the
>>>> wheel is moving* must *also* be moving.
>>>
>>> Ahem. So lesse if I got your "logic" here. The ground is stationary. We
>>> agree with that, right? And the rim of the wheel has points that contact
>>> the ground. But no points on the wheel are stationary? So you are
>>> arguing that the wheel is sliding?
>>
>> No points on the wheel are stationary if the wheel is rolling.
> 
> Only true of wheel is sliding and not rolling. If a point is contact 
> with the ground, then since the ground is not moving it can't be moving.
> 
>>>>> And that means they are in focus while the shutter is open.
>>>>
>>>> Briefly, then they're not. While the shutter is still open. That's
>>>> why they blur.
>>>>
>>>>> So what you have is a LINE of stationary in focus contact points.
>>>>> No?
>>>>
>>>> No.
>>>
>>> So the rim of the wheel is NOT in contact with the ground. Right? Or is
>>> sliding.
>>
>> Obviously the wheel is rolling which means for any real time span
>> the part of the wheel that is in contact with the ground is continuously
>> changeing.
> 
> True. In an ideal case the points on the rim touch the ground one after 
> another, but since the ground is not moving, any point touching the 
> ground can't be moving.
 
All points on the wheel are always moving relative to the ground in any
time period other than zero.

Instantaneous only appears in mathematical equations, not in camera
exposures.
 

-- 
Jim Pennino

Thread

Viewing the spokes Sergio <invalid@invalid.com> - 2016-08-29 12:08 -0500
  Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-08-29 18:00 +0000
    Re: Viewing the spokes benj <benj@nobody.net> - 2016-08-29 21:00 -0400
      Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-08-30 01:14 +0000
        Re: Viewing the spokes benj <benj@nobody.net> - 2016-08-29 22:45 -0400
          Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-08-30 04:14 +0000
            Re: Viewing the spokes The Starmaker <starmaker@ix.netcom.com> - 2016-08-29 21:59 -0700
              Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-08-30 05:16 +0000
                Re: Viewing the spokes The Starmaker <starmaker@ix.netcom.com> - 2016-08-29 23:00 -0700
    Re: Viewing the spokes noTthaTguY <abu.kuanysh05@gmail.com> - 2016-08-29 18:29 -0700
  Re: Viewing the spokes The Starmaker <starmaker@ix.netcom.com> - 2016-08-29 18:29 -0700
  Re: Viewing the spokes The Starmaker <starmaker@ix.netcom.com> - 2016-08-29 18:46 -0700
    Re: Viewing the spokes benj <benj@nobody.net> - 2016-08-30 19:40 -0400
      Re: Viewing the spokes The Starmaker <starmaker@ix.netcom.com> - 2016-08-30 22:07 -0700
        Re: Viewing the spokes The Starmaker <starmaker@ix.netcom.com> - 2016-08-30 23:48 -0700
          Re: Viewing the spokes The Starmaker <starmaker@ix.netcom.com> - 2016-08-31 09:54 -0700
            Re: Viewing the spokes The Starmaker <starmaker@ix.netcom.com> - 2016-09-02 10:00 -0700
              Re: Viewing the spokes noTthaTguY <abu.kuanysh05@gmail.com> - 2016-09-02 13:23 -0700
              Re: Viewing the spokes The Starmaker <starmaker@ix.netcom.com> - 2016-09-03 11:30 -0700
                Red, Blue and Green The Starmaker <starmaker@ix.netcom.com> - 2016-09-03 13:18 -0700
                Re: Red, Blue and Green The Starmaker <starmaker@ix.netcom.com> - 2016-09-03 14:57 -0700
                Re: Red, Blue and Green The Starmaker <starmaker@ix.netcom.com> - 2016-09-03 16:01 -0700
                Re: Red, Blue and Green The Starmaker <starmaker@ix.netcom.com> - 2016-09-04 12:46 -0700
                Re: Red, Blue and Green Ergios <invalid@invalid.com> - 2016-09-07 12:32 -0500
                Re: Red, Blue and Green noTthaTguY <abu.kuanysh05@gmail.com> - 2016-09-08 12:12 -0700
                Red, Blue and Green The Starmaker <starmaker@ix.netcom.com> - 2016-09-07 23:22 -0700
                Re: Red, Blue and Green The Starmaker <starmaker@ix.netcom.com> - 2016-09-03 16:03 -0700
                Re: Red, Blue and Green The Starmaker <starmaker@ix.netcom.com> - 2016-09-03 16:06 -0700
                Re: Red, Blue and Green The Starmaker <starmaker@ix.netcom.com> - 2016-09-20 00:18 -0700
                Re: Red, Blue and Green noTthaTguY <abu.kuanysh05@gmail.com> - 2016-09-20 12:52 -0700
                Re: Red, Blue and Green The Starmaker <starmaker@ix.netcom.com> - 2016-09-07 10:01 -0700
                Re: Red, Blue and Green Gutless Umbrella Carrying Sissy <taustinca@gmail.com> - 2016-09-07 10:12 -0700
                Re: Red, Blue and Green The Starmaker <starmaker@ix.netcom.com> - 2016-09-20 09:47 -0700
        Re: Viewing the spokes noTthaTguY <abu.kuanysh05@gmail.com> - 2016-08-31 14:32 -0700
  Re: Viewing the spokes "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-09-04 11:39 -0700
    Re: Viewing the spokes "hanson" <hanson@quick.net> - 2016-09-04 20:36 -0700
  Re: Viewing the spokes "nuny@bid.nes" <Alien8752@gmail.com> - 2016-09-09 09:08 -0700
    Re: Viewing the spokes noTthaTguY <abu.kuanysh05@gmail.com> - 2016-09-09 12:32 -0700
    Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-09 17:51 -0400
      Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-10 00:10 +0000
        Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-09 20:43 -0400
          Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-10 00:57 +0000
            Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-09 21:07 -0400
              Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-10 01:33 +0000
                Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-12 20:59 -0400
                Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-13 02:41 +0000
      Re: Viewing the spokes "nuny@bid.nes" <Alien8752@gmail.com> - 2016-09-09 19:43 -0700
        Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-12 21:29 -0400
          Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-13 02:43 +0000
          Re: Viewing the spokes noTthaTguY <abu.kuanysh05@gmail.com> - 2016-09-13 13:28 -0700
          Re: Viewing the spokes "nuny@bid.nes" <Alien8752@gmail.com> - 2016-09-13 17:14 -0700
            Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-13 21:52 -0400
              Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-14 05:11 +0000
                Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-15 17:49 -0400
                Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-16 00:50 +0000
                Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-15 21:52 -0400
                Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-16 04:11 +0000
                Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-16 16:58 -0400
                Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-16 21:40 +0000
                Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-16 20:56 -0400
                Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-17 01:47 +0000
                Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-17 17:24 -0400
                Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-18 00:07 +0000
              Re: Viewing the spokes noTthaTguY <abu.kuanysh05@gmail.com> - 2016-09-14 14:26 -0700
                Re: Viewing the spokes noTthaTguY <abu.kuanysh05@gmail.com> - 2016-09-14 15:04 -0700
                Re: Viewing the spokes noTthaTguY <abu.kuanysh05@gmail.com> - 2016-09-16 12:54 -0700
              Re: Viewing the spokes "nuny@bid.nes" <Alien8752@gmail.com> - 2016-09-14 19:47 -0700
                Re: Viewing the spokes benj <nobody@gmail.com> - 2016-09-14 23:24 -0400
                Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-15 05:12 +0000
                Re: Viewing the spokes "nuny@bid.nes" <Alien8752@gmail.com> - 2016-09-15 15:45 -0700
                Re: Viewing the spokes benj <benj@nobody.net> - 2016-09-15 21:36 -0400
                Re: Viewing the spokes jimp@specsol.spam.sux.com - 2016-09-16 02:58 +0000
                Re: Viewing the spokes "nuny@bid.nes" <Alien8752@gmail.com> - 2016-09-18 12:15 -0700
    Re: Viewing the spokes Wally W. <ww84wa@aim.com> - 2016-09-15 09:15 -0400
      Re: Viewing the spokes "nuny@bid.nes" <Alien8752@gmail.com> - 2016-09-15 15:48 -0700
        Re: Viewing the spokes noTthaTguY <abu.kuanysh05@gmail.com> - 2016-09-18 15:33 -0700

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