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Car decelerates...

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  Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-27 19:42 -0800
    Re: Car decelerates... Melzzzzz <mel@zzzzz.com> - 2016-01-28 04:44 +0100
      Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-27 19:48 -0800
        Re: Car decelerates... Sylvia Else <sylvia@not.at.this.address> - 2016-01-28 15:28 +1100
          Re: Car decelerates... mlwozniak@wp.pl - 2016-01-27 22:58 -0800
            Re: Car decelerates... Sylvia Else <sylvia@not.at.this.address> - 2016-01-28 19:57 +1100
              Re: Car decelerates... mlwozniak@wp.pl - 2016-01-28 01:07 -0800
                Re: Car decelerates... Sylvia Else <sylvia@not.at.this.address> - 2016-01-28 22:08 +1100
                  Re: Car decelerates... mlwozniak@wp.pl - 2016-01-28 03:51 -0800
                    Re: Car decelerates... Sylvia Else <sylvia@not.at.this.address> - 2016-01-29 10:53 +1100
                      Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-28 19:31 -0800
                        Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-29 06:40 +0100
                          Re: Car decelerates... mlwozniak@wp.pl - 2016-01-28 22:29 -0800
                          Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-28 22:57 -0800
                            Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-29 08:08 +0100
                              Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-28 23:18 -0800
                                Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-29 08:24 +0100
                                Re: Car decelerates... rotchm <rotchm@gmail.com> - 2016-01-29 06:25 -0800
                                  Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-29 10:19 -0800
                                    Re: Car decelerates... Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 13:30 -0600
                                    Re: Car decelerates... rotchm <rotchm@gmail.com> - 2016-01-29 12:21 -0800
                                    Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-30 10:48 +0100
                                    Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-31 13:55 +0100
                                      Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-31 13:16 -0800
                              Re: Car decelerates... mlwozniak@wp.pl - 2016-01-29 00:35 -0800
                              Re: Car decelerates... Polikwaptiwa <polikw@polikwamail.org> - 2016-01-30 16:32 +0000
                                Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-30 18:02 -0800
                            Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-29 08:19 +0100
                              Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-28 23:23 -0800
                                Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-29 08:28 +0100
                                  Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-28 23:39 -0800
                                    Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-30 09:56 +0100
                                      Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-30 10:09 +0100
                                        Re: Car decelerates... Maciej Woźniak <mlwozniak@wp.pl> - 2016-01-30 11:34 +0100
                            Re: Car decelerates... rotchm <rotchm@gmail.com> - 2016-01-29 06:20 -0800
                        Re: Car decelerates... Sylvia Else <sylvia@not.at.this.address> - 2016-01-29 23:12 +1100
                          Re: Car decelerates... Juan Sebastián <jseb@montserrat.info> - 2016-01-29 12:33 +0000
                            Re: Car decelerates... Sylvia Else <sylvia@not.at.this.address> - 2016-01-30 22:16 +1100
                              Re: Car decelerates... Maciej Woźniak <mlwozniak@wp.pl> - 2016-01-30 12:25 +0100
                                Re: Car decelerates... Sylvia Else <sylvia@not.at.this.address> - 2016-01-30 22:34 +1100
                                  Re: Car decelerates... Maciej Woźniak <mlwozniak@wp.pl> - 2016-01-30 13:45 +0100
                          Re: Car decelerates... mlwozniak@wp.pl - 2016-01-29 04:42 -0800
                        Re: Car decelerates... rotchm <rotchm@gmail.com> - 2016-01-29 06:17 -0800
                          Re: Car decelerates... mlwozniak@wp.pl - 2016-01-29 06:23 -0800
                      Re: Car decelerates... Maciej Woźniak <mlwozniak@wp.pl> - 2016-01-29 06:17 +0100
        Re: Car decelerates... Melzzzzz <mel@zzzzz.com> - 2016-01-28 13:37 +0100
        Re: Car decelerates... moroney@world.std.spaamtrap.com (Michael Moroney) - 2016-01-28 19:33 +0000
    Re: Car decelerates... rotchm <rotchm@gmail.com> - 2016-01-27 20:08 -0800
      Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-27 20:28 -0800
        Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-27 20:34 -0800
          Re: Car decelerates... rotchm <rotchm@gmail.com> - 2016-01-27 20:50 -0800
          Re: Car decelerates... mlwozniak@wp.pl - 2016-01-27 23:00 -0800
            Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-27 23:34 -0800
              Re: Car decelerates... rotchm <rotchm@gmail.com> - 2016-01-28 07:23 -0800
              Re: Car decelerates... Odd Bodkin <bodkinodd@gmail.com> - 2016-01-28 09:59 -0600
                Re: Car decelerates... mlwozniak@wp.pl - 2016-01-28 22:27 -0800
              Re: Car decelerates... Juan Sebastián <jseb@montserrat.info> - 2016-01-28 16:49 +0000
              Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-28 22:29 +0100
        Re: Car decelerates... rotchm <rotchm@gmail.com> - 2016-01-27 20:53 -0800
        Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-28 07:47 +0100
          Re: Car decelerates... Juan Sebastián <jseb@montserrat.info> - 2016-01-28 18:22 +0000
            Re: Car decelerates... Poutnik <poutnik4nntp@gmail.com> - 2016-01-28 22:31 +0100
    Re: Car decelerates... Koobee Wublee <koobee.wublee@gmail.com> - 2016-01-27 23:59 -0800
      Re: Car decelerates... Jon Price <jonelwoodprice@gmail.com> - 2016-01-28 00:19 -0800
    Re: Car decelerates... jamesl51165@gmail.com - 2016-01-28 08:18 -0800
    Re: Car decelerates... Mike Fontenot <mlfasf@comcast.net> - 2016-01-28 09:46 -0700

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#375186

On Friday, January 29, 2016 at 1:19:21 PM UTC-5, Jon Price wrote:

> Don't think I caused it.

Yes you did, in the sense that YOU posited that the car decelerates wrt the ground. Claiming that, the models we use imply that the body in the car will continue to move at constant speed whereas the car slows down. Therefore the body and windshield will collide; they have a varying closing speed wrt the ground frame. In the frame of the car, our models say that the position of the body will be "at²"; no need to invoke gravity or fairies. 

> When you brake your car, does your upper body move forward?

The distance between the body and windshield decreases. In the car frame, "x=at²". What dont you understand in that?

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#375209

Dne 29/01/2016 v 19:19 Jon Price napsal(a):
> Rotchm:
> 
> Don't think I caused it. Think that in this scenario it's factual, objective.
> Car decelerates. Body moves forward.
> 
> That's not a widely accepted and known thing?
> 
> When you brake your car, does your upper body move forward?

Yes, and it is caused by you,
making the driver to decelerate the car
and assigning coordinate system of reference frame
to this decelerating car, making it non inertial
and subjects of rules for non inertial systems.

For non inertial frames is the 2nd Newton motion law
formally  valid only in in modified version.

m . vec_a = vec_F_real + vec_F_fictitious

where fictitious forces are just a formal math artefact
to extend validity of the law for non inertia systems.

For a body to move in non inertial system without relative coordinate
acceleration, there is needed the same but opposite external real force
wrt Fictitious force.

In opposite to linear velocity and rest which are relative,
linear acceleration and angular velocity + accelerations
are absolute in sense there is absolute angular rest.

vec_F_fictitious =
vec_F_fictitious_linear
+ vec_F_fictitious_centrifugal
+ vec_F_fictitious_Coriolis
+ vec_F_fictitious_Euler

For linearly accelerating frame

vec_F_fictitious_linear = m . a_fr,
where a_fr is linear acceleration of frame.

For rotating frame

vec_F_fictitious_centrifugal related to position
= -m . vec_om x ( vec_om x vec_r )
om is angular velocity
. is dot/scalar product of vectors
x is vector product of vectors

vec_F_fictitious_Coriolis related to motion
= -2m . vec_om  x (dvec_r/dt)

vec_F_fictitious_Euler related to frame angular acceleration
= -m . (dvec_om/dt) x vec_r

-- 
Poutnik ( the Czech word for a wanderer )

Knowledge makes great men humble, but small men arrogant.

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#375301

Dne 29/01/2016 v 19:19 Jon Price napsal(a):
> Rotchm:
> 
> Don't think I caused it. Think that in this scenario it's factual, objective.
> Car decelerates. Body moves forward.
> 
Making a car with non zero proper acceleration
to have zero coordinate acceleration

causes objects with zero proper acceleration
to have non zero coordinate acceleration.

https://en.wikipedia.org/wiki/Proper_acceleration


-- 
Poutnik ( the Czech word for a wanderer )

Knowledge makes great men humble, but small men arrogant.

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#375314

Thanks. Helpful reference.

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#375123

W dniu piątek, 29 stycznia 2016 08:08:51 UTC+1 użytkownik Poutnik napisał:

> > Ok, but is space-time curved?
> > 
> Yes, by presence of massive objects like Sun and Earth.
> Not by the car deceleration.

Your poor idiot guru had opposite opinion.

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#375233

Poutnik wrote:

> Dne 29/01/2016 v 07:57 Jon Price napsal(a):
>> Poutnik said:
>> 
>> 
>> The fact the acceleration is for local effects equivalent to locally
>> homogeneous gravity does not mean it is gravity
>> 
>> Ok, but is space-time curved?
>> 
> Yes, by presence of massive objects like Sun and Earth.
> Not by the car deceleration.

Can you prove it. Btw, Relativity says there is no difference. Anyhow, on 
a scale from 1 to 6 you 6 stars from me.

	☆☆☆☆☆☆

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#375273

I suspect that from the cars reference frame, space-time is curved.

The mass/energy case is different in that there is no reference frame from which the space-time curvature goes away.

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#375117

Dne 29/01/2016 v 07:57 Jon Price napsal(a):
> Poutnik said:
> 
> 
> The fact the acceleration is for local effects 
> equivalent to locally homogeneous gravity 
> does not mean it is gravity
> 
> -------
> 
> Ok, but is space-time curved?
> 
Predictions of Special Relativity are valid even for accelerating cases,
in contrary to believe of some people,
thinking SR applies to inertial motion only.

That means it is not curved by acceleration.

If it had been, observers would not have been forced
to inconvenient experiments watching bending light around the Sun,
as they could have managed accelerations in their labs
much stronger then Sun gravitation.


-- 
Poutnik ( the Czech word for a wanderer )

Knowledge makes great men humble, but small men arrogant.

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#375118

I see. Makes sense. Thanks.

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#375120

Dne 29/01/2016 v 08:23 Jon Price napsal(a):
> I see. Makes sense. Thanks.
> 
Aside of that, I think* that space-time curvature is invariant
wrt choice of reference frame/coordinate system.

* but it would need expert to state/claim it.

-- 
Poutnik ( the Czech word for a wanderer )

Knowledge makes great men humble, but small men arrogant.

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#375121

I see. And if invariant, then curvature would exist from grounds reference frame too.
Which it doesn't...

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#375204

Dne 29/01/2016 v 08:39 Jon Price napsal(a):
> I see. And if invariant, then curvature would exist from grounds reference frame too.
> Which it doesn't...
> 
Whicj  it does.

-- 
Poutnik ( the Czech word for a wanderer )

Knowledge makes great men humble, but small men arrogant.

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#375206

Dne 30/01/2016 v 09:56 Poutnik napsal(a):
> Dne 29/01/2016 v 08:39 Jon Price napsal(a):
>> I see. And if invariant, then curvature would exist from grounds reference frame too.
>> Which it doesn't...
>>
> Which  it does.
> 

..but this curvature of space-time metric is very small
and is not related to motion state of the car,
but to masses and distances of Earth and celestial bodies.


-- 
Poutnik ( the Czech word for a wanderer )

Knowledge makes great men humble, but small men arrogant.

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#375210

Użytkownik "Poutnik"  napisał w wiadomości grup 
dyskusyjnych:n8huf6$dto$1@dont-email.me...

Dne 30/01/2016 v 09:56 Poutnik napsal(a):
> Dne 29/01/2016 v 08:39 Jon Price napsal(a):
>> I see. And if invariant, then curvature would exist from grounds 
>> reference frame too.
>> Which it doesn't...
>>
> Which  it does.
>

|..but this curvature of space-time metric is very small
|and is not related to motion state of the car,
|but to masses and distances of Earth and celestial bodies.

Once again, your Great Guru stated differently. 

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#375146

On Friday, January 29, 2016 at 1:57:21 AM UTC-5, Jon Price wrote:

> Ok, but is space-time curved?

No, spacetime doest curve. That is just a very loose description, or a popular description of the equations; like, x = at² doesnt curve; its just an equation. Same thing with general relativity; it gives equations and equations dont curve. But their visual representation "curves".

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#375134

On 29/01/2016 2:31 PM, Jon Price wrote:
> Ok,from cars (noninertial) reference frame which person in car considers to be at rest, persons body moves toward windshield. Person considers this due to a gravitational field.
>
> Is space-time curved here?
>

Probably - it's rare to find cars far from the Earth, the mass of which 
curves space somewhat.

But you're asking whether it's curved as a consequence of the acceleration?

No.

Sylvia.

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#375135

Sylvia Else wrote:

> But you're asking whether it's curved as a consequence of the
> acceleration? No. Sylvia.

In which case you must be able to point out the difference. You can't, 
woman.

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#375213

On 29/01/2016 11:33 PM, Juan Sebastián wrote:
> Sylvia Else wrote:
>
>> But you're asking whether it's curved as a consequence of the
>> acceleration? No. Sylvia.
>
> In which case you must be able to point out the difference. You can't,
> woman.
>

I'm pretty sure that mass-energy has something to do with it. You won't 
find curved space in its absence.

Sylvia.

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#375214

Użytkownik "Sylvia Else"  napisał w wiadomości grup 
dyskusyjnych:dh3kclF9bjuU1@mid.individual.net...

On 29/01/2016 11:33 PM, Juan Sebastián wrote:
> Sylvia Else wrote:
>
>> But you're asking whether it's curved as a consequence of the
>> acceleration? No. Sylvia.
>
> In which case you must be able to point out the difference. You can't,
> woman.
>

|I'm pretty sure

Your Great Guru was pretty sure too, and he stated differently.

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#375215

On 30/01/2016 10:25 PM, Maciej Woźniak wrote:
>
>
> Użytkownik "Sylvia Else"  napisał w wiadomości grup
> dyskusyjnych:dh3kclF9bjuU1@mid.individual.net...
>
> On 29/01/2016 11:33 PM, Juan Sebastián wrote:
>> Sylvia Else wrote:
>>
>>> But you're asking whether it's curved as a consequence of the
>>> acceleration? No. Sylvia.
>>
>> In which case you must be able to point out the difference. You can't,
>> woman.
>>
>
> |I'm pretty sure
>
> Your Great Guru was pretty sure too, and he stated differently.
>

People who don't understand the physics are only too able to misconstrue 
things that are said about it.

Sylvia.

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