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Groups > sci.physics > #546785 > unrolled thread
| Started by | "kquirici@yahoo.com" <kquirici@yahoo.com> |
|---|---|
| First post | 2016-01-20 11:31 -0800 |
| Last post | 2016-01-31 13:51 -0600 |
| Articles | 20 on this page of 147 — 11 participants |
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inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-20 11:31 -0800
Re: inertial frames of reference Sam Wormley <swormley1@gmail.com> - 2016-01-20 13:40 -0600
Re: inertial frames of reference "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-01-20 13:32 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-20 14:14 -0800
Re: inertial frames of reference jimp@specsol.spam.sux.com - 2016-01-21 05:10 +0000
Re: inertial frames of reference Sam Wormley <swormley1@gmail.com> - 2016-01-23 10:58 -0600
Re: inertial frames of reference jimp@specsol.spam.sux.com - 2016-01-23 19:01 +0000
Re: inertial frames of reference Sam Wormley <swormley1@gmail.com> - 2016-01-23 13:10 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-20 16:25 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-20 19:47 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-21 05:37 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-21 08:28 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-21 06:57 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-21 09:15 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-21 07:48 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-22 19:20 -0800
Re: inertial frames of reference Sylvia Else <sylvia@not.at.this.address> - 2016-01-23 14:43 +1100
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-23 12:11 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-23 13:15 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-24 04:48 -0800
Re: inertial frames of reference HVAC <mr.hvac@gmail.com> - 2016-01-24 08:33 -0800
Re: inertial frames of reference benj <none@gmail.com> - 2016-01-25 01:57 -0500
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-25 05:32 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-25 10:56 -0600
Re: inertial frames of reference HVAC <mr.hvac@gmail.com> - 2016-01-26 06:34 -0800
Re: inertial frames of reference benj <none@gmail.com> - 2016-01-26 14:13 -0500
Re: inertial frames of reference HVAC <mr.hvac@gmail.com> - 2016-01-24 08:33 -0800
Re: inertial frames of reference benj <none@gmail.com> - 2016-01-25 01:58 -0500
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-25 10:09 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-25 09:56 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-25 13:29 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-25 09:25 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-25 09:48 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-25 11:55 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-25 14:57 -0800
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-24 16:03 -0800
Re: inertial frames of reference Sam Wormley <swormley1@gmail.com> - 2016-01-24 18:32 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-25 00:50 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-25 10:52 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-25 11:20 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-25 13:34 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-25 15:41 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-26 07:25 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-26 10:54 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-26 15:32 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-27 03:15 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-27 10:18 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-27 12:52 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-27 15:51 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-27 14:09 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-27 16:23 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-28 05:26 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-28 09:10 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-28 10:01 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-28 13:14 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-28 13:02 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-28 16:30 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-28 15:06 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-28 17:15 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-28 18:00 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-29 04:47 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 08:19 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 07:54 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-29 06:44 -0800
Re: inertial frames of reference Sam Wormley <swormley1@gmail.com> - 2016-01-29 08:53 -0600
Re: inertial frames of reference HVAC <mr.hvac@gmail.com> - 2016-01-29 07:07 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-29 07:24 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-29 07:45 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 10:32 -0600
Re: inertial frames of reference HVAC <mr.hvac@gmail.com> - 2016-01-29 08:50 -0800
Re: inertial frames of reference benj <none@gmail.com> - 2016-01-29 12:50 -0500
Re: Ben Jacoby hates the truth because it convicts him. benj <none@gmail.com> - 2016-01-29 14:01 -0500
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 13:27 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 10:52 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-29 09:33 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 12:11 -0600
Re: inertial frames of reference benj <none@gmail.com> - 2016-01-29 12:59 -0500
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 10:08 -0600
Re: inertial frames of reference benj <none@gmail.com> - 2016-01-29 12:39 -0500
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 12:16 -0600
Re: inertial frames of reference benj <none@gmail.com> - 2016-01-29 14:06 -0500
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 14:40 -0600
Re: inertial frames of reference HVAC <mr.hvac@gmail.com> - 2016-01-29 04:56 -0800
Re: inertial frames of reference HVAC <mr.hvac@gmail.com> - 2016-01-29 04:56 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-27 17:56 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-27 18:57 -0800
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-28 05:43 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-28 09:13 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-28 09:19 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-28 14:47 -0800
Re: inertial frames of reference Sam Wormley <swormley1@gmail.com> - 2016-01-28 16:52 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-28 17:10 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-29 01:13 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 08:16 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-29 09:26 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 12:05 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-29 10:52 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 14:31 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-30 07:37 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-31 13:58 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-02-01 03:05 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-02-01 09:40 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-29 09:34 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 12:14 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-29 10:58 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-29 14:39 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-30 07:43 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-31 14:01 -0600
Re: inertial frames of reference benj <none@gmail.com> - 2016-01-29 14:12 -0500
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-28 08:59 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-28 09:03 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-28 11:40 -0600
Re: inertial frames of reference kenseto <setoken@att.net> - 2016-01-30 11:36 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-25 10:44 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-23 05:19 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-23 06:10 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-29 10:06 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-31 07:23 -0800
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-01-31 08:53 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-31 11:54 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-31 14:04 -0600
Re: inertial frames of reference xxein1@att.net - 2016-01-31 15:01 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-31 19:07 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-31 13:54 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-01-31 15:04 -0800
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-02-01 03:37 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-02-01 04:18 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-02-01 04:26 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-02-01 09:52 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-02-01 08:34 -0800
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-02-01 10:40 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-02-01 12:55 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-02-01 13:55 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-02-01 16:38 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-02-02 07:19 -0600
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-02-02 09:53 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-02-02 12:55 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-02-01 16:27 -0800
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-02-02 01:39 -0800
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-02-02 05:49 -0800
Re: inertial frames of reference jay moseley <jaymoseley@hotmail.com> - 2016-02-02 10:49 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-02-02 13:20 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-02-02 09:43 -0600
Re: inertial frames of reference "kquirici@yahoo.com" <kquirici@yahoo.com> - 2016-02-01 04:20 -0800
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-02-01 09:55 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-02-01 09:43 -0600
Re: inertial frames of reference Odd Bodkin <bodkinodd@gmail.com> - 2016-01-31 13:51 -0600
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| From | "kquirici@yahoo.com" <kquirici@yahoo.com> |
|---|---|
| Date | 2016-01-20 11:31 -0800 |
| Subject | inertial frames of reference |
| Message-ID | <b59ea8fd-7891-46a0-96b7-5653549889a4@googlegroups.com> |
Wikipedia on Special Relativity: [Special Relativity is based on two principles:] "(1) that the laws of physics are invariant (i.e. identical) in all inertial systems (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is the same for all observers, regardless of the motion of the light source" A frame of reference is a set of coordinates established by an observer. Does the quote above mean simply that the laws of physics are identical in two frames of reference that are not accelerating relative to each other? I.e., that 'inertial' is a RELATIVE term, not an ABSOLUTE term. Or is absolute? As stated it seems to imply somehow absoluteness.
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| From | Sam Wormley <swormley1@gmail.com> |
|---|---|
| Date | 2016-01-20 13:40 -0600 |
| Message-ID | <5oqdnSgTNuJffwLLnZ2dnUU7-XednZ2d@giganews.com> |
| In reply to | #546785 |
On 1/20/16 1:31 PM, kquirici@yahoo.com wrote: > Wikipedia on Special Relativity: > > [Special Relativity is based on two principles:] > > "(1) that the laws of physics are invariant (i.e. identical) in all inertial systems (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is the same for all observers, regardless of the motion of the light source" > > A frame of reference is a set of coordinates established by an observer. > > Does the quote above mean simply that the laws of physics are identical in two frames of reference that are not accelerating relative to each other? I.e., that 'inertial' is a RELATIVE term, not an ABSOLUTE term. > > Or is absolute? As stated it seems to imply somehow absoluteness. > All motion is relative. The train and the train station each has an inertial frame of reference--those frames have a relative motion with respect to each other. -- sci.physics is an unmoderated newsgroup dedicated to the discussion of physics, news from the physics community, and physics-related social issues.
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| From | "reber g=emc^2" <herbertglazier0@gmail.com> |
|---|---|
| Date | 2016-01-20 13:32 -0800 |
| Message-ID | <788a1153-0f44-4584-bcd4-807c26e4105b@googlegroups.com> |
| In reply to | #546792 |
On Wednesday, January 20, 2016 at 11:40:53 AM UTC-8, Sam Wormley wrote: > On 1/20/16 1:31 PM, kquirici@yahoo.com wrote: > > Wikipedia on Special Relativity: > > > > [Special Relativity is based on two principles:] > > > > "(1) that the laws of physics are invariant (i.e. identical) in all inertial systems (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is the same for all observers, regardless of the motion of the light source" > > > > A frame of reference is a set of coordinates established by an observer. > > > > Does the quote above mean simply that the laws of physics are identical in two frames of reference that are not accelerating relative to each other? I.e., that 'inertial' is a RELATIVE term, not an ABSOLUTE term. > > > > Or is absolute? As stated it seems to imply somehow absoluteness. > > > > All motion is relative. The train and the train station each has an > inertial frame of reference--those frames have a relative motion > with respect to each other. > > -- > > sci.physics is an unmoderated newsgroup dedicated > to the discussion of physics, news from the physics > community, and physics-related social issues. You can tell which is moving if you use your brain. TreBert
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| From | "kquirici@yahoo.com" <kquirici@yahoo.com> |
|---|---|
| Date | 2016-01-20 14:14 -0800 |
| Message-ID | <b57afa94-46f4-46d5-9875-786dfe937347@googlegroups.com> |
| In reply to | #546819 |
On Wednesday, January 20, 2016 at 4:32:18 PM UTC-5, reber g=emc^2 wrote: > On Wednesday, January 20, 2016 at 11:40:53 AM UTC-8, Sam Wormley wrote: > > On 1/20/16 1:31 PM, kquirici@yahoo.com wrote: > > > Wikipedia on Special Relativity: > > > > > > [Special Relativity is based on two principles:] > > > > > > "(1) that the laws of physics are invariant (i.e. identical) in all inertial systems (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is the same for all observers, regardless of the motion of the light source" > > > > > > A frame of reference is a set of coordinates established by an observer. > > > > > > Does the quote above mean simply that the laws of physics are identical in two frames of reference that are not accelerating relative to each other? I.e., that 'inertial' is a RELATIVE term, not an ABSOLUTE term. > > > > > > Or is absolute? As stated it seems to imply somehow absoluteness. > > > > > > > All motion is relative. The train and the train station each has an > > inertial frame of reference--those frames have a relative motion > > with respect to each other. > > > > -- > > > > sci.physics is an unmoderated newsgroup dedicated > > to the discussion of physics, news from the physics > > community, and physics-related social issues. > > You can tell which is moving if you use your brain. TreBert Thanks for your replies except they don't reply to the explicit questions I asked. I'd appreciate someone with understanding of physics to understand and address my actual questions. I don't THINK they're meaningless.
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| From | jimp@specsol.spam.sux.com |
|---|---|
| Date | 2016-01-21 05:10 +0000 |
| Message-ID | <ar56nc-ckf.ln1@mail.specsol.com> |
| In reply to | #546792 |
Sam Wormley <swormley1@gmail.com> wrote: > On 1/20/16 1:31 PM, kquirici@yahoo.com wrote: >> Wikipedia on Special Relativity: >> >> [Special Relativity is based on two principles:] >> >> "(1) that the laws of physics are invariant (i.e. identical) in all inertial systems (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is the same for all observers, regardless of the motion of the light source" >> >> A frame of reference is a set of coordinates established by an observer. >> >> Does the quote above mean simply that the laws of physics are identical in two frames of reference that are not accelerating relative to each other? I.e., that 'inertial' is a RELATIVE term, not an ABSOLUTE term. >> >> Or is absolute? As stated it seems to imply somehow absoluteness. >> > > All motion is relative. The train and the train station each has an > inertial frame of reference--those frames have a relative motion > with respect to each other. The question was about acceleration, not motion. -- Jim Pennino
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| From | Sam Wormley <swormley1@gmail.com> |
|---|---|
| Date | 2016-01-23 10:58 -0600 |
| Message-ID | <VIadndb8q_y6LD7LnZ2dnUU7-QednZ2d@giganews.com> |
| In reply to | #546912 |
On 1/20/16 11:10 PM, jimp@specsol.spam.sux.com wrote: > > The question was about acceleration, not motion. > > You should re-read the OP, jimp. Furthermore, you're obsessive nature is outta control, and your absolute contempt and total disgust are addressed in these Anger Management classes. You, jimp, need these services: > http://yellowpages.com/rancho-cucamonga-ca/anger-management-classes -- sci.physics is an unmoderated newsgroup dedicated to the discussion of physics, news from the physics community, and physics-related social issues.
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| From | jimp@specsol.spam.sux.com |
|---|---|
| Date | 2016-01-23 19:01 +0000 |
| Message-ID | <f8vcnc-j29.ln1@mail.specsol.com> |
| In reply to | #547538 |
Sam Wormley <swormley1@gmail.com> wrote: > On 1/20/16 11:10 PM, jimp@specsol.spam.sux.com wrote: >> >> The question was about acceleration, not motion. >> >> > > You should re-read the OP, jimp. Furthermore, you're obsessive nature What makes you think you are so special you are exempt from copyrights? -- Jim Pennino
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| From | Sam Wormley <swormley1@gmail.com> |
|---|---|
| Date | 2016-01-23 13:10 -0600 |
| Message-ID | <OYCdnYPlVPanTT7LnZ2dnUU7-Q-dnZ2d@giganews.com> |
| In reply to | #547592 |
On 1/23/16 1:01 PM, jimp@specsol.spam.sux.com wrote: > What makes you think you are so special you are exempt from copyrights? > You should re-read the OP, jimp. Furthermore, you're obsessive nature is outta control, and your absolute contempt and total disgust are addressed in these Anger Management classes. You, jimp, need these services: > http://yellowpages.com/rancho-cucamonga-ca/anger-management-classes -- sci.physics is an unmoderated newsgroup dedicated to the discussion of physics, news from the physics community, and physics-related social issues.
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| From | Odd Bodkin <bodkinodd@gmail.com> |
|---|---|
| Date | 2016-01-20 16:25 -0600 |
| Message-ID | <n7p1h5$1tfn$1@gioia.aioe.org> |
| In reply to | #546785 |
On 1/20/2016 1:31 PM, kquirici@yahoo.com wrote: > Wikipedia on Special Relativity: > > [Special Relativity is based on two principles:] > > "(1) that the laws of physics are invariant (i.e. identical) in all inertial systems > (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is > the same for all observers, regardless of the motion of the light source" > > A frame of reference is a set of coordinates established by an observer. > > Does the quote above mean simply that the laws of physics are identical in two frames of > reference that are not accelerating relative to each other? I.e., that 'inertial' is a > RELATIVE term, not an ABSOLUTE term. > > Or is absolute? As stated it seems to imply somehow absoluteness. > I believe inertial reference frames can be distinguished from other reference frames as being those where the first law of motion (or if you like, conservation of momentum) holds. So it's a little more than a relative statement. Otherwise, you could ask if two frames that are in constant motion relative to each other but which are both accelerating satisfy these premises. In a special relativity sense, the answer is no, I *think*. -- Odd Bodkin --- maker of fine toys, tools, tables
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| From | "kquirici@yahoo.com" <kquirici@yahoo.com> |
|---|---|
| Date | 2016-01-20 19:47 -0800 |
| Message-ID | <d1ea27af-63a6-44a3-9bbc-ce4f7ded2957@googlegroups.com> |
| In reply to | #546829 |
On Wednesday, January 20, 2016 at 5:25:58 PM UTC-5, Odd Bodkin wrote: > On 1/20/2016 1:31 PM, kquirici@yahoo.com wrote: > > Wikipedia on Special Relativity: > > > > [Special Relativity is based on two principles:] > > > > "(1) that the laws of physics are invariant (i.e. identical) in all inertial systems > > (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is > > the same for all observers, regardless of the motion of the light source" > > > > A frame of reference is a set of coordinates established by an observer. > > > > Does the quote above mean simply that the laws of physics are identical in two frames of > > reference that are not accelerating relative to each other? I.e., that 'inertial' is a > > RELATIVE term, not an ABSOLUTE term. > > > > Or is absolute? As stated it seems to imply somehow absoluteness. > > > > I believe inertial reference frames can be distinguished from other > reference frames as being those where the first law of motion (or if you > like, conservation of momentum) holds. So it's a little more than a > relative statement. Otherwise, you could ask if two frames that are in > constant motion relative to each other but which are both accelerating > satisfy these premises. In a special relativity sense, the answer is no, > I *think*. > > > -- > Odd Bodkin --- maker of fine toys, tools, tables Thanks. Can you give me an example of a frame of reference that is NOT an inertial frame of reference>
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| From | "kquirici@yahoo.com" <kquirici@yahoo.com> |
|---|---|
| Date | 2016-01-21 05:37 -0800 |
| Message-ID | <af61c831-8cbb-41a5-9822-3483ebf848e7@googlegroups.com> |
| In reply to | #546901 |
On Wednesday, January 20, 2016 at 10:47:37 PM UTC-5, kqui...@yahoo.com wrote: > On Wednesday, January 20, 2016 at 5:25:58 PM UTC-5, Odd Bodkin wrote: > > On 1/20/2016 1:31 PM, kquirici@yahoo.com wrote: > > > Wikipedia on Special Relativity: > > > > > > [Special Relativity is based on two principles:] > > > > > > "(1) that the laws of physics are invariant (i.e. identical) in all inertial systems > > > (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is > > > the same for all observers, regardless of the motion of the light source" > > > > > > A frame of reference is a set of coordinates established by an observer. > > > > > > Does the quote above mean simply that the laws of physics are identical in two frames of > > > reference that are not accelerating relative to each other? I.e., that 'inertial' is a > > > RELATIVE term, not an ABSOLUTE term. > > > > > > Or is absolute? As stated it seems to imply somehow absoluteness. > > > > > > > I believe inertial reference frames can be distinguished from other > > reference frames as being those where the first law of motion (or if you > > like, conservation of momentum) holds. So it's a little more than a > > relative statement. Otherwise, you could ask if two frames that are in > > constant motion relative to each other but which are both accelerating > > satisfy these premises. In a special relativity sense, the answer is no, > > I *think*. > > > > > > -- > > Odd Bodkin --- maker of fine toys, tools, tables > > Thanks. Can you give me an example of a frame of reference that is NOT an inertial frame of reference> A non-inertial frame of reference could be constructed inside a spaceship that is travelling in orbit around for example a planet. Imagine a large room. A ball is projected in some direction. Because of the rotation around the planet the path of the ball will be measurably deflected by the Coriolis 'acceleration' or 'force'. Since there is no visible force INSIDE the frame of reference, the frame can't be inertial (which requires objects in motion stay in motion at the same speed in the same direction unless subject to an external force). OK. Since gravity pervades the universe, there is NO possible inertial frame of reference (if you measure things to enough precision). Is this correct?
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| From | Odd Bodkin <bodkinodd@gmail.com> |
|---|---|
| Date | 2016-01-21 08:28 -0600 |
| Message-ID | <n7qpte$ho4$1@gioia.aioe.org> |
| In reply to | #546901 |
On 1/20/2016 9:47 PM, kquirici@yahoo.com wrote: > On Wednesday, January 20, 2016 at 5:25:58 PM UTC-5, Odd Bodkin wrote: >> On 1/20/2016 1:31 PM, kquirici@yahoo.com wrote: >>> Wikipedia on Special Relativity: >>> >>> [Special Relativity is based on two principles:] >>> >>> "(1) that the laws of physics are invariant (i.e. identical) in all inertial systems >>> (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is >>> the same for all observers, regardless of the motion of the light source" >>> >>> A frame of reference is a set of coordinates established by an observer. >>> >>> Does the quote above mean simply that the laws of physics are identical in two frames of >>> reference that are not accelerating relative to each other? I.e., that 'inertial' is a >>> RELATIVE term, not an ABSOLUTE term. >>> >>> Or is absolute? As stated it seems to imply somehow absoluteness. >>> >> >> I believe inertial reference frames can be distinguished from other >> reference frames as being those where the first law of motion (or if you >> like, conservation of momentum) holds. So it's a little more than a >> relative statement. Otherwise, you could ask if two frames that are in >> constant motion relative to each other but which are both accelerating >> satisfy these premises. In a special relativity sense, the answer is no, >> I *think*. >> >> >> -- >> Odd Bodkin --- maker of fine toys, tools, tables > > Thanks. Can you give me an example of a frame of reference that is NOT an inertial frame of reference> > Absolutely. Take a case where there is a ball whirling on the end of a string, and one of the axes in your reference frame lies along the string and follows the ball as it whirls around. Now in this frame, you'll notice something unusual. The ball appears to be in equilibrium, even though there is only one force that appears to be acting on it -- the one caused by the string. Now you have an object in equilibrium even though there is an unbalanced force acting on the object, a violation of Newton's first law. Now, you can try to fix that by hypothesizing an outward force on the ball, opposite in direction to the string, but there is no agent you can point to that is responsible for acting on the ball that way. (This is why centrifugal "force" is called a fictitious force.) Another way you can recognize it is that the size of the force is always proportional to the mass of the object. This fact is interesting in its own right and has deep consequences that leads to a 20th century theory of gravity. -- Odd Bodkin --- maker of fine toys, tools, tables
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| From | "kquirici@yahoo.com" <kquirici@yahoo.com> |
|---|---|
| Date | 2016-01-21 06:57 -0800 |
| Message-ID | <70edde1c-425a-4192-96e9-795f4481f02d@googlegroups.com> |
| In reply to | #546982 |
On Thursday, January 21, 2016 at 9:28:03 AM UTC-5, Odd Bodkin wrote: > On 1/20/2016 9:47 PM, kquirici@yahoo.com wrote: > > On Wednesday, January 20, 2016 at 5:25:58 PM UTC-5, Odd Bodkin wrote: > >> On 1/20/2016 1:31 PM, kquirici@yahoo.com wrote: > >>> Wikipedia on Special Relativity: > >>> > >>> [Special Relativity is based on two principles:] > >>> > >>> "(1) that the laws of physics are invariant (i.e. identical) in all inertial systems > >>> (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is > >>> the same for all observers, regardless of the motion of the light source" > >>> > >>> A frame of reference is a set of coordinates established by an observer. > >>> > >>> Does the quote above mean simply that the laws of physics are identical in two frames of > >>> reference that are not accelerating relative to each other? I.e., that 'inertial' is a > >>> RELATIVE term, not an ABSOLUTE term. > >>> > >>> Or is absolute? As stated it seems to imply somehow absoluteness. > >>> > >> > >> I believe inertial reference frames can be distinguished from other > >> reference frames as being those where the first law of motion (or if you > >> like, conservation of momentum) holds. So it's a little more than a > >> relative statement. Otherwise, you could ask if two frames that are in > >> constant motion relative to each other but which are both accelerating > >> satisfy these premises. In a special relativity sense, the answer is no, > >> I *think*. > >> > >> > >> -- > >> Odd Bodkin --- maker of fine toys, tools, tables > > > > Thanks. Can you give me an example of a frame of reference that is NOT an inertial frame of reference> > > > > Absolutely. Take a case where there is a ball whirling on the end of a > string, and one of the axes in your reference frame lies along the > string and follows the ball as it whirls around. > > Now in this frame, you'll notice something unusual. The ball appears to > be in equilibrium, even though there is only one force that appears to > be acting on it -- the one caused by the string. Now you have an object > in equilibrium even though there is an unbalanced force acting on the > object, a violation of Newton's first law. Now, you can try to fix that > by hypothesizing an outward force on the ball, opposite in direction to > the string, but there is no agent you can point to that is responsible > for acting on the ball that way. (This is why centrifugal "force" is > called a fictitious force.) > > Another way you can recognize it is that the size of the force is always > proportional to the mass of the object. This fact is interesting in its > own right and has deep consequences that leads to a 20th century theory > of gravity. > > -- > Odd Bodkin --- maker of fine toys, tools, tables I like that thought experiment. I think of the ball pulling on the string but (usually) not the equal and opposite force of the string pulling on the ball. And the notion of the missing balancing force that the more general notion of equilibrium leads to. Cool.
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| From | Odd Bodkin <bodkinodd@gmail.com> |
|---|---|
| Date | 2016-01-21 09:15 -0600 |
| Message-ID | <n7qslt$q4c$1@gioia.aioe.org> |
| In reply to | #546988 |
On 1/21/2016 8:57 AM, kquirici@yahoo.com wrote: > I like that thought experiment. I think of the ball pulling on the string but (usually) > not the equal and opposite force of the string pulling on the ball. And the notion of > the missing balancing force that the more general notion of equilibrium leads to. Cool. One more comment here because I spotted a mistake that I once made while learning this subject too -- I guess it's a common mistake. It's tempting to say that equilibrium means that the string pulls on the ball with a force equal to how much the ball is pulling on the string. But no, that's not what equilibrium means. Equilibrium means that all the forces on a SINGLE object cancel out. So choose the ball OR the string, but stick with that one. Now, if you choose the ball, then look at all the forces acting ON THE BALL and ask if they cancel out. Since only the string is acting on the ball, there can be no way all the forces acting on the ball cancel out. -- Odd Bodkin --- maker of fine toys, tools, tables
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| From | "kquirici@yahoo.com" <kquirici@yahoo.com> |
|---|---|
| Date | 2016-01-21 07:48 -0800 |
| Message-ID | <4d84b95f-4d82-4044-8d6c-df367801cdd6@googlegroups.com> |
| In reply to | #546990 |
On Thursday, January 21, 2016 at 10:15:52 AM UTC-5, Odd Bodkin wrote: > On 1/21/2016 8:57 AM, kquirici@yahoo.com wrote: > > I like that thought experiment. I think of the ball pulling on the string but (usually) > > not the equal and opposite force of the string pulling on the ball. And the notion of > > the missing balancing force that the more general notion of equilibrium leads to. Cool. > > One more comment here because I spotted a mistake that I once made while > learning this subject too -- I guess it's a common mistake. > > It's tempting to say that equilibrium means that the string pulls on the > ball with a force equal to how much the ball is pulling on the string. > But no, that's not what equilibrium means. Equilibrium means that all > the forces on a SINGLE object cancel out. So choose the ball OR the > string, but stick with that one. Now, if you choose the ball, then look > at all the forces acting ON THE BALL and ask if they cancel out. Since > only the string is acting on the ball, there can be no way all the > forces acting on the ball cancel out. > > > -- > Odd Bodkin --- maker of fine toys, tools, tables Good ooint. I think I was sort of making that mistake too. One of the virtues of fuzzy and insufficiently worked-out thinking is that one at times only sort of makes mistakes.
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| From | "kquirici@yahoo.com" <kquirici@yahoo.com> |
|---|---|
| Date | 2016-01-22 19:20 -0800 |
| Message-ID | <5b7b0578-51f4-4dc5-babb-ab121fbac75a@googlegroups.com> |
| In reply to | #546995 |
On Thursday, January 21, 2016 at 10:48:58 AM UTC-5, kqui...@yahoo.com wrote: > On Thursday, January 21, 2016 at 10:15:52 AM UTC-5, Odd Bodkin wrote: > > On 1/21/2016 8:57 AM, kquirici@yahoo.com wrote: > > > I like that thought experiment. I think of the ball pulling on the string but (usually) > > > not the equal and opposite force of the string pulling on the ball. And the notion of > > > the missing balancing force that the more general notion of equilibrium leads to. Cool. > > > > One more comment here because I spotted a mistake that I once made while > > learning this subject too -- I guess it's a common mistake. > > > > It's tempting to say that equilibrium means that the string pulls on the > > ball with a force equal to how much the ball is pulling on the string. > > But no, that's not what equilibrium means. Equilibrium means that all > > the forces on a SINGLE object cancel out. So choose the ball OR the > > string, but stick with that one. Now, if you choose the ball, then look > > at all the forces acting ON THE BALL and ask if they cancel out. Since > > only the string is acting on the ball, there can be no way all the > > forces acting on the ball cancel out. > > > > > > -- > > Odd Bodkin --- maker of fine toys, tools, tables > > Good ooint. I think I was sort of making that mistake too. One of the virtues of fuzzy and insufficiently worked-out thinking is that one at times only sort of makes mistakes. So what about this question/suggestion from the first post: there are no inertial frames of reference because the universe is filled with gravitational fields and hence all objects are accelerating (however slightly). ?
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| From | Sylvia Else <sylvia@not.at.this.address> |
|---|---|
| Date | 2016-01-23 14:43 +1100 |
| Message-ID | <dggb7mFd1jpU1@mid.individual.net> |
| In reply to | #547390 |
On 23/01/2016 2:20 PM, kquirici@yahoo.com wrote: > On Thursday, January 21, 2016 at 10:48:58 AM UTC-5, kqui...@yahoo.com wrote: >> On Thursday, January 21, 2016 at 10:15:52 AM UTC-5, Odd Bodkin wrote: >>> On 1/21/2016 8:57 AM, kquirici@yahoo.com wrote: >>>> I like that thought experiment. I think of the ball pulling on the string but (usually) >>>> not the equal and opposite force of the string pulling on the ball. And the notion of >>>> the missing balancing force that the more general notion of equilibrium leads to. Cool. >>> >>> One more comment here because I spotted a mistake that I once made while >>> learning this subject too -- I guess it's a common mistake. >>> >>> It's tempting to say that equilibrium means that the string pulls on the >>> ball with a force equal to how much the ball is pulling on the string. >>> But no, that's not what equilibrium means. Equilibrium means that all >>> the forces on a SINGLE object cancel out. So choose the ball OR the >>> string, but stick with that one. Now, if you choose the ball, then look >>> at all the forces acting ON THE BALL and ask if they cancel out. Since >>> only the string is acting on the ball, there can be no way all the >>> forces acting on the ball cancel out. >>> >>> >>> -- >>> Odd Bodkin --- maker of fine toys, tools, tables >> >> Good ooint. I think I was sort of making that mistake too. One of the virtues of fuzzy and insufficiently worked-out thinking is that one at times only sort of makes mistakes. > > So what about this question/suggestion from the first post: > > there are no inertial frames of reference because the universe is filled with gravitational fields and hence all objects are accelerating (however slightly). > > ? > It's not so much the fact that they're accelerating that prevents them from being inertial. If you found a volume of space in which the gravitational field was constant, and then placed yourself in free fall inside the volume, then you would be in an inertial frame even though you would be accelerating. However, without looking outside the volume, you'd have no way of detecting the fact that you were accelerating. That is, you'd find that the laws of physics were the same as for any other inertial frame. In practice, one doesn't find volumes of space like that. However, it's easy enough to find volumes in which the field changes very little, and the laws of physics in such a place have to be correspondingly close to those in a genuinely inertial frame. Indeed, this is the basis on which general relativity is built. Sylvia.
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| From | Odd Bodkin <bodkinodd@gmail.com> |
|---|---|
| Date | 2016-01-23 12:11 -0600 |
| Message-ID | <n80fo6$1tm3$13@gioia.aioe.org> |
| In reply to | #547390 |
On 1/22/2016 9:20 PM, kquirici@yahoo.com wrote: > On Thursday, January 21, 2016 at 10:48:58 AM UTC-5, kqui...@yahoo.com wrote: >> On Thursday, January 21, 2016 at 10:15:52 AM UTC-5, Odd Bodkin wrote: >>> On 1/21/2016 8:57 AM, kquirici@yahoo.com wrote: >>>> I like that thought experiment. I think of the ball pulling on the string but (usually) >>>> not the equal and opposite force of the string pulling on the ball. And the notion of >>>> the missing balancing force that the more general notion of equilibrium leads to. Cool. >>> >>> One more comment here because I spotted a mistake that I once made while >>> learning this subject too -- I guess it's a common mistake. >>> >>> It's tempting to say that equilibrium means that the string pulls on the >>> ball with a force equal to how much the ball is pulling on the string. >>> But no, that's not what equilibrium means. Equilibrium means that all >>> the forces on a SINGLE object cancel out. So choose the ball OR the >>> string, but stick with that one. Now, if you choose the ball, then look >>> at all the forces acting ON THE BALL and ask if they cancel out. Since >>> only the string is acting on the ball, there can be no way all the >>> forces acting on the ball cancel out. >>> >>> >>> -- >>> Odd Bodkin --- maker of fine toys, tools, tables >> >> Good ooint. I think I was sort of making that mistake too. One of the virtues of > fuzzy and insufficiently worked-out thinking is that one at times only sort of makes mistakes. > > So what about this question/suggestion from the first post: > > there are no inertial frames of reference because the universe is filled with gravitational > fields and hence all objects are accelerating (however slightly). > > ? > Be careful. Remember what I told you the definition of an inertial frame is. I didn't say anything about it being gravity free. What DID I say? -- Odd Bodkin --- maker of fine toys, tools, tables
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| From | "kquirici@yahoo.com" <kquirici@yahoo.com> |
|---|---|
| Date | 2016-01-23 13:15 -0800 |
| Message-ID | <d5989ece-91d7-4a78-8a11-e0b6cef5f4ac@googlegroups.com> |
| In reply to | #547574 |
On Saturday, January 23, 2016 at 1:11:32 PM UTC-5, Odd Bodkin wrote: > On 1/22/2016 9:20 PM, kquirici@yahoo.com wrote: > > On Thursday, January 21, 2016 at 10:48:58 AM UTC-5, kqui...@yahoo.com wrote: > >> On Thursday, January 21, 2016 at 10:15:52 AM UTC-5, Odd Bodkin wrote: > >>> On 1/21/2016 8:57 AM, kquirici@yahoo.com wrote: > >>>> I like that thought experiment. I think of the ball pulling on the string but (usually) > >>>> not the equal and opposite force of the string pulling on the ball. And the notion of > >>>> the missing balancing force that the more general notion of equilibrium leads to. Cool. > >>> > >>> One more comment here because I spotted a mistake that I once made while > >>> learning this subject too -- I guess it's a common mistake. > >>> > >>> It's tempting to say that equilibrium means that the string pulls on the > >>> ball with a force equal to how much the ball is pulling on the string. > >>> But no, that's not what equilibrium means. Equilibrium means that all > >>> the forces on a SINGLE object cancel out. So choose the ball OR the > >>> string, but stick with that one. Now, if you choose the ball, then look > >>> at all the forces acting ON THE BALL and ask if they cancel out. Since > >>> only the string is acting on the ball, there can be no way all the > >>> forces acting on the ball cancel out. > >>> > >>> > >>> -- > >>> Odd Bodkin --- maker of fine toys, tools, tables > >> > >> Good ooint. I think I was sort of making that mistake too. One of the virtues of > > fuzzy and insufficiently worked-out thinking is that one at times only sort of makes mistakes. > > > > So what about this question/suggestion from the first post: > > > > there are no inertial frames of reference because the universe is filled with gravitational > > fields and hence all objects are accelerating (however slightly). > > > > ? > > > > Be careful. Remember what I told you the definition of an inertial frame > is. I didn't say anything about it being gravity free. What DID I say? > > > -- > Odd Bodkin --- maker of fine toys, tools, tables OK, you said an inertial frame of reference is one in which momentum is conserved. Arggh. My train of reasoning is this (after duly consulting Wikipedia): momentum is a 3-dimensional vector - (mv1, mv2, mv3). Yet anywhere in the universe if I'm in a box and throw a ball, won't its momentum change in an inexplicable (however tiny) way, since there's a net gravitational force of which my old pal the Coriolis Force is the efficient cause? I may be getting confused about the meaning of 'frame of reference'. My operating definition is an orthogonal coordinate system set up by an observer. Am I missing something about what a frame of reference is?
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| From | "kquirici@yahoo.com" <kquirici@yahoo.com> |
|---|---|
| Date | 2016-01-24 04:48 -0800 |
| Message-ID | <fc15ead1-2cee-4e1e-a9bb-31ecc987e0b9@googlegroups.com> |
| In reply to | #547641 |
On Saturday, January 23, 2016 at 4:16:01 PM UTC-5, kqui...@yahoo.com wrote: > On Saturday, January 23, 2016 at 1:11:32 PM UTC-5, Odd Bodkin wrote: > > On 1/22/2016 9:20 PM, kquirici@yahoo.com wrote: > > > On Thursday, January 21, 2016 at 10:48:58 AM UTC-5, kqui...@yahoo.com wrote: > > >> On Thursday, January 21, 2016 at 10:15:52 AM UTC-5, Odd Bodkin wrote: > > >>> On 1/21/2016 8:57 AM, kquirici@yahoo.com wrote: > > >>>> I like that thought experiment. I think of the ball pulling on the string but (usually) > > >>>> not the equal and opposite force of the string pulling on the ball. And the notion of > > >>>> the missing balancing force that the more general notion of equilibrium leads to. Cool. > > >>> > > >>> One more comment here because I spotted a mistake that I once made while > > >>> learning this subject too -- I guess it's a common mistake. > > >>> > > >>> It's tempting to say that equilibrium means that the string pulls on the > > >>> ball with a force equal to how much the ball is pulling on the string. > > >>> But no, that's not what equilibrium means. Equilibrium means that all > > >>> the forces on a SINGLE object cancel out. So choose the ball OR the > > >>> string, but stick with that one. Now, if you choose the ball, then look > > >>> at all the forces acting ON THE BALL and ask if they cancel out. Since > > >>> only the string is acting on the ball, there can be no way all the > > >>> forces acting on the ball cancel out. > > >>> > > >>> > > >>> -- > > >>> Odd Bodkin --- maker of fine toys, tools, tables > > >> > > >> Good ooint. I think I was sort of making that mistake too. One of the virtues of > > > fuzzy and insufficiently worked-out thinking is that one at times only sort of makes mistakes. > > > > > > So what about this question/suggestion from the first post: > > > > > > there are no inertial frames of reference because the universe is filled with gravitational > > > fields and hence all objects are accelerating (however slightly). > > > > > > ? > > > > > > > Be careful. Remember what I told you the definition of an inertial frame > > is. I didn't say anything about it being gravity free. What DID I say? > > > > > > -- > > Odd Bodkin --- maker of fine toys, tools, tables > > OK, you said an inertial frame of reference is one in which momentum is conserved. Arggh. My train of reasoning is this (after duly consulting Wikipedia): > > momentum is a 3-dimensional vector - (mv1, mv2, mv3). > > Yet anywhere in the universe if I'm in a box and throw a ball, won't its momentum change in an inexplicable (however tiny) way, since there's a net gravitational force of which my old pal the Coriolis Force is the efficient cause? > > I may be getting confused about the meaning of 'frame of reference'. My operating definition is an orthogonal coordinate system set up by an observer. Am I missing something about what a frame of reference is? Aha. Coriolis is due to rotating frames of reference, not to gravity. same with Odd Bodkin's example of centrifugal force. Hence Coriolis is not the evidence that gravity by itself causes all reference frames to be non-inertial. My haring off after Coriolis was just fuzzy thinking. I can't help but think however that if I'm in a room with no windows and I throw something against the wall it falls. For no visible reason. Within my frame of reference, the room, there is no force causing this change of the momentum vector. Again, it's this notion of frames of reference that bothers me. There's something abstract going on here I don't get. There's something understood that I don't understand. Well, at least I found my Coriolis error. I'll find this one. Thanks.
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