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Groups > sci.physics.relativity > #597693 > unrolled thread
| Started by | The Starmaker <starmaker@ix.netcom.com> |
|---|---|
| First post | 2022-12-16 22:29 -0800 |
| Last post | 2022-12-17 23:54 -0800 |
| Articles | 20 on this page of 92 — 16 participants |
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What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-16 22:29 -0800
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-17 09:31 -0800
Re: What is the force that the Earth used to keep us on the ground? Richard Hertz <hertz778@gmail.com> - 2022-12-17 10:26 -0800
Re: What is the force that the Earth used to keep us on the ground? "mitchr...@gmail.com" <mitchrae3323@gmail.com> - 2022-12-17 10:44 -0800
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-17 11:20 -0800
Re: What is the force that the Earth used to keep us on the ground? "Paul B. Andersen" <paul.b.andersen@paulba.no> - 2022-12-17 22:31 +0100
Re: What is the force that the Earth used to keep us on the ground? Richard Hertz <hertz778@gmail.com> - 2022-12-17 13:40 -0800
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-17 16:02 -0800
Re: What is the force that the Earth used to keep us on the ground? Richard Hertz <hertz778@gmail.com> - 2022-12-17 16:18 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-17 22:18 -0800
Cretin Pat Dolan demonstrates once again that his ibecility extends to basic mathematics "Dono." <eggy20011951@gmail.com> - 2022-12-17 16:57 -0800
Re: Cretin Pat Dolan demonstrates once again that his ibecility extends to basic mathematics patdolan <patdolan@comcast.net> - 2022-12-17 17:24 -0800
Re: Cretin Pat Dolan demonstrates once again that his ibecility extends to basic mathematics "Dono." <eggy20011951@gmail.com> - 2022-12-17 17:45 -0800
Re: Cretin Pat Dolan demonstrates once again that his ibecility extends to basic mathematics patdolan <patdolan@comcast.net> - 2022-12-17 17:51 -0800
Re: Cretin Pat Dolan demonstrates once again that his ibecility extends to basic mathematics "Dono." <eggy20011951@gmail.com> - 2022-12-17 17:53 -0800
Re: Cretin Pat Dolan demonstrates once again that his ibecility extends to basic mathematics Athel Cornish-Bowden <acornish@imm.cnrs.fr> - 2022-12-18 09:45 +0100
Re: Cretin Pat Dolan demonstrates once again that his ibecility extends to basic mathematics Maciej Wozniak <maluwozniak@gmail.com> - 2022-12-18 00:49 -0800
Re: Cretin Pat Dolan demonstrates once again that his ibecility extends to basic mathematics patdolan <patdolan@comcast.net> - 2022-12-17 18:20 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-17 22:11 -0800
Re: What is the force that the Earth used to keep us on the ground? "Paul B. Andersen" <paul.b.andersen@paulba.no> - 2022-12-18 13:09 +0100
Re: What is the force that the Earth used to keep us on the ground? Vitaliy Bazzoli <zvt@viavzl.oi> - 2022-12-18 18:06 +0000
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-18 12:15 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-19 11:44 -0800
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-17 15:51 -0800
Crank Pat Dolan puts foot in mouth "Dono." <eggy20011951@gmail.com> - 2022-12-17 16:53 -0800
Re: Crank Pat Dolan puts foot in mouth Richard Hertz <hertz778@gmail.com> - 2022-12-17 17:21 -0800
Re: Crank Pat Dolan puts foot in mouth "Dono." <eggy20011951@gmail.com> - 2022-12-17 17:23 -0800
Re: What is the force that the Earth used to keep us on the ground? "Paul B. Andersen" <paul.b.andersen@paulba.no> - 2022-12-18 13:19 +0100
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-18 10:23 -0800
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-18 10:29 -0800
Re: What is the force that the Earth used to keep us on the ground? "Dono." <eggy20011951@gmail.com> - 2022-12-18 10:30 -0800
Re: What is the force that the Earth used to keep us on the ground? Athel Cornish-Bowden <acornish@imm.cnrs.fr> - 2022-12-18 19:34 +0100
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-19 11:52 -0800
Re: What is the force that the Earth used to keep us on the ground? Paul Alsing <pnalsing@gmail.com> - 2022-12-19 19:58 -0800
Re: What is the force that the Earth used to keep us on the ground? Maciej Wozniak <maluwozniak@gmail.com> - 2022-12-19 23:52 -0800
Re: What is the force that the Earth used to keep us on the ground? Athel Cornish-Bowden <acornish@imm.cnrs.fr> - 2022-12-20 08:53 +0100
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-20 00:37 -0800
Re: What is the force that the Earth used to keep us on the ground? Athel Cornish-Bowden <acornish@imm.cnrs.fr> - 2022-12-20 11:11 +0100
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-20 10:34 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-20 10:43 -0800
Re: What is the force that the Earth used to keep us on the ground? "mitchr...@gmail.com" <mitchrae3323@gmail.com> - 2022-12-20 11:01 -0800
Re: What is the force that the Earth used to keep us on the ground? Volney <volney@invalid.invalid> - 2022-12-21 00:09 -0500
Re: What is the force that the Earth used to keep us on the ground? whodat <whodaat@void.nowgre.com> - 2022-12-20 23:32 -0600
Re: What is the force that the Earth used to keep us on the ground? Volney <volney@invalid.invalid> - 2022-12-21 15:22 -0500
Re: What is the force that the Earth used to keep us on the ground? Michelle Africano <nccr@amenica.he> - 2022-12-21 20:27 +0000
Re: What is the force that the Earth used to keep us on the ground? nospam@de-ster.demon.nl (J. J. Lodder) - 2022-12-21 21:52 +0100
Re: What is the force that the Earth used to keep us on the ground? Tom Roberts <tjoberts137@sbcglobal.net> - 2022-12-21 16:52 -0600
Re: What is the force that the Earth used to keep us on the ground? Michelle Africano <nccr@amenica.he> - 2022-12-21 23:00 +0000
Re: What is the force that the Earth used to keep us on the ground? nospam@de-ster.demon.nl (J. J. Lodder) - 2022-12-22 14:14 +0100
Re: What is the force that the Earth used to keep us on the ground? whodat <whodaat@void.nowgre.com> - 2022-12-21 14:52 -0600
Re: What is the force that the Earth used to keep us on the ground? Tom Roberts <tjoberts137@sbcglobal.net> - 2022-12-21 17:03 -0600
Re: What is the force that the Earth used to keep us on the ground? Richard Hertz <hertz778@gmail.com> - 2022-12-21 15:25 -0800
Re: What is the force that the Earth used to keep us on the ground? Richard Hertz <hertz778@gmail.com> - 2022-12-21 16:51 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-21 19:40 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-21 19:58 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-22 14:38 -0800
Re: What is the force that the Earth used to keep us on the ground? whodat <whodaat@void.nowgre.com> - 2022-12-21 21:55 -0600
Re: What is the force that the Earth used to keep us on the ground? Volney <volney@invalid.invalid> - 2022-12-23 02:26 -0500
Crank Dick Hertz fails classical kinemnatics "Dono." <eggy20011951@gmail.com> - 2022-12-23 11:08 -0800
Re: What is the force that the Earth used to keep us on the ground? Michelle Africano <nccr@amenica.he> - 2022-12-21 23:25 +0000
Re: What is the force that the Earth used to keep us on the ground? whodat <whodaat@void.nowgre.com> - 2022-12-21 21:53 -0600
Re: What is the force that the Earth used to keep us on the ground? Rico Amato <toaa@araocco.rt> - 2022-12-22 16:04 +0000
Re: What is the force that the Earth used to keep us on the ground? whodat <whodaat@void.nowgre.com> - 2022-12-22 12:41 -0600
Re: What is the force that the Earth used to keep us on the ground? nospam@de-ster.demon.nl (J. J. Lodder) - 2022-12-22 11:53 +0100
Re: What is the force that the Earth used to keep us on the ground? Rico Amato <toaa@araocco.rt> - 2022-12-22 15:57 +0000
Re: What is the force that the Earth used to keep us on the ground? Volney <volney@invalid.invalid> - 2022-12-22 23:43 -0500
Re: What is the force that the Earth used to keep us on the ground? Rico Amato <toaa@araocco.rt> - 2022-12-23 18:59 +0000
Re: What is the force that the Earth used to keep us on the ground? whodat <whodaat@void.nowgre.com> - 2022-12-23 16:43 -0600
Re: What is the force that the Earth used to keep us on the ground? nospam@de-ster.demon.nl (J. J. Lodder) - 2022-12-22 11:53 +0100
Re: What is the force that the Earth used to keep us on the ground? Athel Cornish-Bowden <acornish@imm.cnrs.fr> - 2022-12-22 09:44 +0100
Re: What is the force that the Earth used to keep us on the ground? Maciej Wozniak <maluwozniak@gmail.com> - 2022-12-22 02:15 -0800
Re: What is the force that the Earth used to keep us on the ground? Richard Hertz <hertz778@gmail.com> - 2022-12-21 05:18 -0800
Re: What is the force that the Earth used to keep us on the ground? Volney <volney@invalid.invalid> - 2022-12-21 15:38 -0500
Re: What is the force that the Earth used to keep us on the ground? "mitchr...@gmail.com" <mitchrae3323@gmail.com> - 2022-12-21 11:43 -0800
Re: What is the force that the Earth used to keep us on the ground? Michelle Africano <nccr@amenica.he> - 2022-12-21 19:53 +0000
Re: What is the force that the Earth used to keep us on the ground? "mitchr...@gmail.com" <mitchrae3323@gmail.com> - 2022-12-21 20:14 -0800
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-21 20:51 -0800
Re: What is the force that the Earth used to keep us on the ground? "mitchr...@gmail.com" <mitchrae3323@gmail.com> - 2023-01-21 12:04 -0800
Re: What is the force that the Earth used to keep us on the ground? whodat <whodaat@void.nowgre.com> - 2022-12-20 14:15 -0600
Re: What is the force that the Earth used to keep us on the ground? "Paul B. Andersen" <paul.b.andersen@paulba.no> - 2022-12-19 14:23 +0100
Re: What is the force that the Earth used to keep us on the ground? Richard Hertz <hertz778@gmail.com> - 2022-12-19 05:54 -0800
Re: What is the force that the Earth used to keep us on the ground? "Paul B. Andersen" <paul.b.andersen@paulba.no> - 2022-12-20 20:20 +0100
Re: What is the force that the Earth used to keep us on the ground? Maciej Wozniak <maluwozniak@gmail.com> - 2022-12-20 12:03 -0800
Re: What is the force that the Earth used to keep us on the ground? Maciej Wozniak <maluwozniak@gmail.com> - 2022-12-19 08:46 -0800
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-19 09:21 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-19 11:38 -0800
Re: What is the force that the Earth used to keep us on the ground? patdolan <patdolan@comcast.net> - 2022-12-19 11:52 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-19 23:03 -0800
Re: What is the force that the Earth used to keep us on the ground? "mitchr...@gmail.com" <mitchrae3323@gmail.com> - 2022-12-17 18:40 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-17 22:09 -0800
Re: What is the force that the Earth used to keep us on the ground? The Starmaker <starmaker@ix.netcom.com> - 2022-12-17 23:47 -0800
Re: What is the force that the Earth used to keep us on the ground? Paul Alsing <pnalsing@gmail.com> - 2022-12-17 23:54 -0800
Page 3 of 5 — ← Prev page 1 2 [3] 4 5 Next page →
| From | "mitchr...@gmail.com" <mitchrae3323@gmail.com> |
|---|---|
| Date | 2022-12-20 11:01 -0800 |
| Message-ID | <238058ce-b644-4853-b31a-3ca0f50f0624n@googlegroups.com> |
| In reply to | #597930 |
On Tuesday, December 20, 2022 at 10:43:38 AM UTC-8, The Starmaker wrote: > patdolan wrote: > > > > On Tuesday, December 20, 2022 at 2:11:54 AM UTC-8, Athel Cornish-Bowden wrote: > > > On 2022-12-20 08:37:25 +0000, patdolan said: > > > > > > > > > > > [ … ] > > > > The phinest physicists of our time are some of the phinest phools in > > > > the world. But only we normies appreciate this fact. > > > > Now as regards YV and his advisors, do you have a disagreement with > > > > them concerning the YV version of the GR force equation? If so, > > > > please explain. Let me refresh your memory concerning that equation: > > > > > > > > The normal force upon the bottom face of a brick produced by the > > > > tabletop upon which it is resting is equal to (mass) x (spacetime > > > > curvature) x (velocity through time) > > > Descending into complete gibberish, I see. Oh well. > > > > Please go to the time stamped link I provided and watch YV and his felt tip pen teach the equation from GR that demonstrates why one needs to accelerate just to stand still on the surface of the earth. If this is gibberish to you, as it is to me, know that it is coming from your side. Not mine. If you choose to disavow YV and his stable of GR mentors, then do so, right here in this forum. It is time to stop asking questions and state your position clearly. > > > > I am not entrapable by questions because I am critiquing and not professing. Strange you have not already learned this subtle point of argumentation. Thou shouldst not have been old before thou hadst been wise, Athel Cornish Mainly in England. > > > -- > > > Athel -- French and British, living in Marseilles for 36+ years; mainly > > > in England until 1987. > You need to understand the textbook defintion of the > word..."accelerate". Coming to a stop is...accelerating. No. That is slowing down. There is both acceleration and deceleration. And there is still forward motion... Mitchell Raemsch > -- > The Starmaker -- To question the unquestionable, ask the unaskable, > to think the unthinkable, mention the unmentionable, say the unsayable, > and challenge > the unchallengeable.
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| From | Volney <volney@invalid.invalid> |
|---|---|
| Date | 2022-12-21 00:09 -0500 |
| Message-ID | <tnu4e7$v1qk$1@dont-email.me> |
| In reply to | #597933 |
On 12/20/2022 2:01 PM, mitchr...@gmail.com wrote: > On Tuesday, December 20, 2022 at 10:43:38 AM UTC-8, The Starmaker wrote: >> You need to understand the textbook defintion of the >> word..."accelerate". Coming to a stop is...accelerating. > > No. That is slowing down. There is both acceleration and deceleration. > And there is still forward motion... Roy, he said the textbook definition of accelerate. Roy, deceleration is nothing more than a negative acceleration. See, Roy? That's another use for negative numbers, which you don't understand!
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| From | whodat <whodaat@void.nowgre.com> |
|---|---|
| Date | 2022-12-20 23:32 -0600 |
| Message-ID | <k0fk40FkmgnU1@mid.individual.net> |
| In reply to | #597956 |
On 12/20/2022 11:09 PM, Volney wrote: > On 12/20/2022 2:01 PM, mitchr...@gmail.com wrote: >> On Tuesday, December 20, 2022 at 10:43:38 AM UTC-8, The Starmaker wrote: > >>> You need to understand the textbook defintion of the >>> word..."accelerate". Coming to a stop is...accelerating. >> >> No. That is slowing down. There is both acceleration and deceleration. >> And there is still forward motion... > > Roy, he said the textbook definition of accelerate. Roy, deceleration is > nothing more than a negative acceleration. See, Roy? That's another use > for negative numbers, which you don't understand! I hate to have to point this out, but since acceleration is any change in speed or direction there is no such a thing has "negative acceleration." That expression is an impossibility as a science based word. The concept of slowing down exists of course, but the nomenclature is limited by the broad definition of the word accelerate. What frosts me even more is that I have to acknowledge that our resident troll is correct.
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| From | Volney <volney@invalid.invalid> |
|---|---|
| Date | 2022-12-21 15:22 -0500 |
| Message-ID | <tnvpt9$1449k$1@dont-email.me> |
| In reply to | #597957 |
On 12/21/2022 12:32 AM, whodat wrote: > On 12/20/2022 11:09 PM, Volney wrote: >> On 12/20/2022 2:01 PM, mitchr...@gmail.com wrote: >>> On Tuesday, December 20, 2022 at 10:43:38 AM UTC-8, The Starmaker wrote: >> >>>> You need to understand the textbook defintion of the >>>> word..."accelerate". Coming to a stop is...accelerating. >>> >>> No. That is slowing down. There is both acceleration and deceleration. >>> And there is still forward motion... >> >> Roy, he said the textbook definition of accelerate. Roy, deceleration >> is nothing more than a negative acceleration. See, Roy? That's another >> use for negative numbers, which you don't understand! > > I hate to have to point this out, but since acceleration is any change > in speed or direction there is no such a thing has "negative > acceleration." That expression is an impossibility as a science > based word. The concept of slowing down exists of course, but the > nomenclature is limited by the broad definition of the word accelerate. > > What frosts me even more is that I have to acknowledge that our resident > troll is correct. > In ordinary mechanics (physics) there is no deceleration, acceleration is a vector which can add to or subtract from the velocity vector [over time] or act at an angle such as an orbiting planet. Its components can be positive or negative. In one dimension it can be represented as a positive or negative number along the x axis. An exception is friction, which always opposes the velocity relative to whatever it has frictional contact with. This opposition to the motion is seen as deceleration. Slide an object across the floor and it slows and stops on the floor or "decelerates". When it stops there is no longer any deceleration (or acceleration for that matter), the acceleration is 0.
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| From | Michelle Africano <nccr@amenica.he> |
|---|---|
| Date | 2022-12-21 20:27 +0000 |
| Message-ID | <tnvq89$13r7b$5@dont-email.me> |
| In reply to | #597987 |
Volney wrote: > In ordinary mechanics (physics) there is no deceleration, acceleration > is a vector which can add to or subtract from the velocity vector [over > time] or act at an angle such as an orbiting planet. idiot, */_that's_NOT_deceleration_/*. A deceleration is *_a_lowering_* acceleration, hence _still_an_acceleration_. Amazing with you *_electronic_engineers_*.
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| From | nospam@de-ster.demon.nl (J. J. Lodder) |
|---|---|
| Date | 2022-12-21 21:52 +0100 |
| Message-ID | <1q3c1ki.1cbyo3n17phr51N%nospam@de-ster.demon.nl> |
| In reply to | #597987 |
Volney <volney@invalid.invalid> wrote: > On 12/21/2022 12:32 AM, whodat wrote: > > On 12/20/2022 11:09 PM, Volney wrote: > >> On 12/20/2022 2:01 PM, mitchr...@gmail.com wrote: > >>> On Tuesday, December 20, 2022 at 10:43:38 AM UTC-8, The Starmaker wrote: > >> > >>>> You need to understand the textbook defintion of the > >>>> word..."accelerate". Coming to a stop is...accelerating. > >>> > >>> No. That is slowing down. There is both acceleration and deceleration. > >>> And there is still forward motion... > >> > >> Roy, he said the textbook definition of accelerate. Roy, deceleration > >> is nothing more than a negative acceleration. See, Roy? That's another > >> use for negative numbers, which you don't understand! > > > > I hate to have to point this out, but since acceleration is any change > > in speed or direction there is no such a thing has "negative > > acceleration." That expression is an impossibility as a science > > based word. The concept of slowing down exists of course, but the > > nomenclature is limited by the broad definition of the word accelerate. > > > > What frosts me even more is that I have to acknowledge that our resident > > troll is correct. > > > > In ordinary mechanics (physics) there is no deceleration, acceleration > is a vector which can add to or subtract from the velocity vector [over > time] or act at an angle such as an orbiting planet. Its components can > be positive or negative. In one dimension it can be represented as a > positive or negative number along the x axis. > > An exception is friction, which always opposes the velocity relative to > whatever it has frictional contact with. This opposition to the motion > is seen as deceleration. Slide an object across the floor and it slows > and stops on the floor or "decelerates". When it stops there is no > longer any deceleration (or acceleration for that matter), the > acceleration is 0. For a spinning object, such as a billiard ball, frictional forces can be forward, or sideways, Jan
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| From | Tom Roberts <tjoberts137@sbcglobal.net> |
|---|---|
| Date | 2022-12-21 16:52 -0600 |
| Message-ID | <D-mdncaRbJSCEz7-nZ2dnZfqlJxg4p2d@giganews.com> |
| In reply to | #597992 |
On 12/21/22 2:52 PM, J. J. Lodder wrote: > Volney <volney@invalid.invalid> wrote: >> friction [...] always opposes the velocity relative to whatever it >> has frictional contact with. > For a spinning object, such as a billiard ball, frictional forces > can be forward, or sideways, Hmmm. At each point of the ball that is in contact with the table, the frictional force on that point of the ball is opposite to the velocity of that point relative to the table. While the ball is hard, the table is not; at any instant there are multiple points of the ball in contact with the table. The spin of the ball can make those points' velocity vectors not be parallel to the velocity vector of the ball's center-of-mass. The ball is quite rigid, and one must sum the forces on all those points to get the net force on the ball. Tom Roberts
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| From | Michelle Africano <nccr@amenica.he> |
|---|---|
| Date | 2022-12-21 23:00 +0000 |
| Message-ID | <to0370$14snj$3@dont-email.me> |
| In reply to | #598001 |
Tom Roberts wrote: > On 12/21/22 2:52 PM, J. J. Lodder wrote: >> Volney <volney@invalid.invalid> wrote: >>> friction [...] always opposes the velocity relative to whatever it has >>> frictional contact with. >> For a spinning object, such as a billiard ball, frictional forces can >> be forward, or sideways, > > Hmmm. At each point of the ball that is in contact with the table, the > frictional force on that point of the ball _is_opposite_to_the_velocity_ > of that point relative to the table. While the ball is hard, the table > is not; at any instant there are multiple points of the ball in contact > with the table. The spin of the ball can make those points' velocity > vectors *_not_be_parallel_to_the_velocity_vector_* of the ball's > center-of-mass. The ball is quite rigid, and one *_must_sum_the_forces_* > on all those points to get the net force on the ball. absolutely. It can also become *towards_the_same_direction*, if the ball spins forward.
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| From | nospam@de-ster.demon.nl (J. J. Lodder) |
|---|---|
| Date | 2022-12-22 14:14 +0100 |
| Message-ID | <1q3d081.1eshig018ac82wN%nospam@de-ster.demon.nl> |
| In reply to | #598001 |
Tom Roberts <tjoberts137@sbcglobal.net> wrote: > On 12/21/22 2:52 PM, J. J. Lodder wrote: > > Volney <volney@invalid.invalid> wrote: > >> friction [...] always opposes the velocity relative to whatever it > >> has frictional contact with. > > For a spinning object, such as a billiard ball, frictional forces > > can be forward, or sideways, > > Hmmm. At each point of the ball that is in contact with the table, the > frictional force on that point of the ball is opposite to the velocity > of that point relative to the table. It must be nice to be this clairvoyant about what actually happens at this tiny indented interface. I wouldn't be so sure. FYI, conditions at the interface can be quite extreme, with enough slippage to cause burn marks. > While the ball is hard, the table > is not; at any instant there are multiple points of the ball in contact > with the table. The spin of the ball can make those points' velocity > vectors not be parallel to the velocity vector of the ball's > center-of-mass. The ball is quite rigid, and one must sum the forces on > all those points to get the net force on the ball. Certainly, and there is no ground for believing that the instantaneous friction force must be locally opposite to the local velocity. (apart from theoretical prejudice) Remember hat the table is compacted felt: it has long range order compared to the size of the contact point. (hairs) And yes, it is quite remarkable what the masters are capable of, (see under trick shots) Jan
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| From | whodat <whodaat@void.nowgre.com> |
|---|---|
| Date | 2022-12-21 14:52 -0600 |
| Message-ID | <k0ha0uFsh2nU1@mid.individual.net> |
| In reply to | #597987 |
On 12/21/2022 2:22 PM, Volney wrote: > On 12/21/2022 12:32 AM, whodat wrote: >> On 12/20/2022 11:09 PM, Volney wrote: >>> On 12/20/2022 2:01 PM, mitchr...@gmail.com wrote: >>>> On Tuesday, December 20, 2022 at 10:43:38 AM UTC-8, The Starmaker >>>> wrote: >>> >>>>> You need to understand the textbook defintion of the >>>>> word..."accelerate". Coming to a stop is...accelerating. >>>> >>>> No. That is slowing down. There is both acceleration and deceleration. >>>> And there is still forward motion... >>> >>> Roy, he said the textbook definition of accelerate. Roy, deceleration >>> is nothing more than a negative acceleration. See, Roy? That's >>> another use for negative numbers, which you don't understand! >> >> I hate to have to point this out, but since acceleration is any change >> in speed or direction there is no such a thing has "negative >> acceleration." That expression is an impossibility as a science >> based word. The concept of slowing down exists of course, but the >> nomenclature is limited by the broad definition of the word accelerate. >> >> What frosts me even more is that I have to acknowledge that our resident >> troll is correct. >> > > In ordinary mechanics (physics) there is no deceleration, acceleration > is a vector which can add to or subtract from the velocity vector [over > time] or act at an angle such as an orbiting planet. Its components can > be positive or negative. In one dimension it can be represented as a > positive or negative number along the x axis. > > An exception is friction, which always opposes the velocity relative to > whatever it has frictional contact with. This opposition to the motion > is seen as deceleration. Slide an object across the floor and it slows > and stops on the floor or "decelerates". When it stops there is no > longer any deceleration (or acceleration for that matter), the > acceleration is 0. The interesting thing about living languages is that users are permitted, perhaps even encouraged, to innovate usage of words including the invention of new words. From that standpoint I have no personal objection to the use of "deceleration" in common speech. In settings such as this one, a semi-formal science discussion group, it is a necessity that scientifically accepted verbiage be used. One can make an argument for deceleration as you have done, and make a compelling case where narrowing the definition seems appropriate. I have no nit to pick with you about "decelerate." As a matter of general usage in a science setting it doesn't have credence. You've made a narrow case that doesn't appear to have any avenue for valid dissent. Of course the acceptance of the definition of words in the science community is similar to that in definitions and acceptability of words in the general usage community albeit it is a smaller subset where the science community is concerned. Interestingly enough my mother and her generation used the expression "slow up!" I always thought that an oxymoron but in the generation before me that was well accepted in general usage, so who was I to object. So I never objected although I found it grating. Now, before someone accuses me of babbling, I retire from this discussion.
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| From | Tom Roberts <tjoberts137@sbcglobal.net> |
|---|---|
| Date | 2022-12-21 17:03 -0600 |
| Message-ID | <aYidnSzKVvkvDT7-nZ2dnZfqlJ9h4p2d@giganews.com> |
| In reply to | #597993 |
On 12/21/22 2:52 PM, whodat wrote: > [...] In common speech, "acceleration" means an increase in speed, and "deceleration" means a decrease in speed. In physics, "deceleration" is not used, and "acceleration" is ambiguous, as it could mean "3-acceleration", "proper acceleration", "4-acceleration", or "coordinate acceleration". In context here it means 3-acceleration, a 3-vector that is the time derivative of an object's 3-velocity. Note that the acceleration 3-vector can be opposite in direction from an object's 3-velocity, in which case it is a reduction in the velocity. Tom Roberts
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| From | Richard Hertz <hertz778@gmail.com> |
|---|---|
| Date | 2022-12-21 15:25 -0800 |
| Message-ID | <4fadb2a1-2e92-4af3-b0aa-e20947bfb8c4n@googlegroups.com> |
| In reply to | #598004 |
On Wednesday, December 21, 2022 at 8:03:21 PM UTC-3, Tom Roberts wrote: <snip> > In common speech, "acceleration" means an increase in speed, and > "deceleration" means a decrease in speed. > > In physics, "deceleration" is not used, and "acceleration" is ambiguous, > as it could mean "3-acceleration", "proper acceleration", > "4-acceleration", or "coordinate acceleration". In context here it means > 3-acceleration, a 3-vector that is the time derivative of an object's > 3-velocity. Note that the acceleration 3-vector can be opposite in > direction from an object's 3-velocity, in which case it is a reduction > in the velocity. Please, take note about how relativity ruined your connection with reality. You can't write a post without using: 3-vector, 4-vector, "proper" whatever, manifolds, Lorentz boost (rotation-free transform), and similar GR jargon. You are so detached from reality, that you can't communicate with other people no more. Furthermore, you don't have "common speech", nor you have "erudite speech". Yours is incomprehensible unless you talk with another relativist. UNLESS you are showing off here, like a peacock. Maybe this is the real cause. Like an anglophile born in Brooklyn, pretending to be British by speaking like upper class there. Hubble was one of them. There are millions of pretenders about so many things. SAD. There are 35 synonyms, antonyms, idiomatic expressions, and related words for pretender. You won't like any of them. BE SIMPLER, NORMAL.
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| From | Richard Hertz <hertz778@gmail.com> |
|---|---|
| Date | 2022-12-21 16:51 -0800 |
| Message-ID | <24c9503b-857e-4a9e-93de-761104ebea0an@googlegroups.com> |
| In reply to | #598006 |
1-vector, 2-vector, n-vector....... fuck it. Given a(t) for an object moving along x-axis, then IF da/dt = 0, the acceleration peaked or is constant. IF da/dt > 0, the acceleration is increasing, so the object is gaining velocity (speed). It's ACCELERATING. IF da/dt < 0, the acceleration is decreasing, so the object is losing velocity (speed). It's DECELERATING, like in the re-entry of a spacecraft.
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| From | The Starmaker <starmaker@ix.netcom.com> |
|---|---|
| Date | 2022-12-21 19:40 -0800 |
| Message-ID | <63A3D1AA.4330@ix.netcom.com> |
| In reply to | #598009 |
Richard Hertz wrote: > > 1-vector, 2-vector, n-vector....... fuck it. > > Given a(t) for an object moving along x-axis, then > > IF da/dt = 0, the acceleration peaked or is constant. > > IF da/dt > 0, the acceleration is increasing, so the object is gaining velocity (speed). It's ACCELERATING. > > IF da/dt < 0, the acceleration is decreasing, so the object is losing velocity (speed). It's DECELERATING, like in > the re-entry of a spacecraft. NOT losing velocity....it's called a 'change' in velosity. Any change in velosity increasing or decreasing is called...acceleration. -- The Starmaker -- To question the unquestionable, ask the unaskable, to think the unthinkable, mention the unmentionable, say the unsayable, and challenge the unchallengeable.
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| From | The Starmaker <starmaker@ix.netcom.com> |
|---|---|
| Date | 2022-12-21 19:58 -0800 |
| Message-ID | <63A3D5F1.3BCF@ix.netcom.com> |
| In reply to | #598010 |
The Starmaker wrote: > > Richard Hertz wrote: > > > > 1-vector, 2-vector, n-vector....... fuck it. > > > > Given a(t) for an object moving along x-axis, then > > > > IF da/dt = 0, the acceleration peaked or is constant. > > > > IF da/dt > 0, the acceleration is increasing, so the object is gaining velocity (speed). It's ACCELERATING. > > > > IF da/dt < 0, the acceleration is decreasing, so the object is losing velocity (speed). It's DECELERATING, like in > > the re-entry of a spacecraft. > > NOT losing velocity....it's called a 'change' in velosity. > > Any change in velosity increasing or decreasing is > called...acceleration. > So there is an acceleration when velocity changes either in magnitude (an increase or decrease in speed) or in direction, or both. https://openstax.org/books/college-physics-2e/pages/2-4-acceleration#:~:text=So%20there%20is%20an%20acceleration%20when%20velocity%20changes%20either%20in%20magnitude%20(an%20increase%20or%20decrease%20in%20speed)%20or%20in%20direction%2C%20or%20both. -- The Starmaker -- To question the unquestionable, ask the unaskable, to think the unthinkable, mention the unmentionable, say the unsayable, and challenge the unchallengeable.
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| From | The Starmaker <starmaker@ix.netcom.com> |
|---|---|
| Date | 2022-12-22 14:38 -0800 |
| Message-ID | <63A4DC61.476@ix.netcom.com> |
| In reply to | #598013 |
The Starmaker wrote: > > The Starmaker wrote: > > > > Richard Hertz wrote: > > > > > > 1-vector, 2-vector, n-vector....... fuck it. > > > > > > Given a(t) for an object moving along x-axis, then > > > > > > IF da/dt = 0, the acceleration peaked or is constant. > > > > > > IF da/dt > 0, the acceleration is increasing, so the object is gaining velocity (speed). It's ACCELERATING. > > > > > > IF da/dt < 0, the acceleration is decreasing, so the object is losing velocity (speed). It's DECELERATING, like in > > > the re-entry of a spacecraft. > > > > NOT losing velocity....it's called a 'change' in velosity. > > > > Any change in velosity increasing or decreasing is > > called...acceleration. > > > > So there is an acceleration when velocity changes either in magnitude (an increase or decrease in speed) or in direction, or both. > https://openstax.org/books/college-physics-2e/pages/2-4-acceleration#:~:text=So%20there%20is%20an%20acceleration%20when%20velocity%20changes%20either%20in%20magnitude%20(an%20increase%20or%20decrease%20in%20speed Keep in mind that these are just 'textbooks' definitions, and are corrupted information...so they need to be taken with a grain of salt. All 'textbooks' information are monopoly controlled and the truth and facts are whatever they say it is the truth and facts. Has nothing to do with the truth or the facts. Mush. For example...I'm sure everyone here notices Google search engine is being censored, so you might have trouble finding information 'that used to be there and no longer is'. And they shorten the search results for certain topics. So you have to use Tor to see more unfiltered results. Is there Life on Mars? Or....water? What does the 'textbooks' say? Ask any 10 year old the question "Is Pluto a planet?" You might be surprised by their answers... it all depends what garbage they are reading. Garbage in... -- The Starmaker -- To question the unquestionable, ask the unaskable, to think the unthinkable, mention the unmentionable, say the unsayable, and challenge the unchallengeable.
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| From | whodat <whodaat@void.nowgre.com> |
|---|---|
| Date | 2022-12-21 21:55 -0600 |
| Message-ID | <k0i2paF1p4fU2@mid.individual.net> |
| In reply to | #598009 |
On 12/21/2022 6:51 PM, Richard Hertz wrote: > 1-vector, 2-vector, n-vector....... fuck it. > > Given a(t) for an object moving along x-axis, then > > IF da/dt = 0, the acceleration peaked or is constant. > > IF da/dt > 0, the acceleration is increasing, so the object is gaining velocity (speed). It's ACCELERATING. > > IF da/dt < 0, the acceleration is decreasing, so the object is losing velocity (speed). It's DECELERATING, like in > the re-entry of a spacecraft. When you do not have a command of basic linguistic skills you should probably avoid expressing your opinions about more advanced concepts. Best of luck though.
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| From | Volney <volney@invalid.invalid> |
|---|---|
| Date | 2022-12-23 02:26 -0500 |
| Message-ID | <to3l7t$1lfrq$1@dont-email.me> |
| In reply to | #598009 |
On 12/21/2022 7:51 PM, Richard Hertz wrote: > 1-vector, 2-vector, n-vector....... fuck it. One dimensional case is strictly along a single axis. Speeds, accelerations can be positive or negative. Two dimensional or more: You have to deal with vectors pointing in directions other than strictly forward and backward. Orbits, curves and so forth. > > Given a(t) for an object moving along x-axis, then What is a? Acceleration? Position? > > IF da/dt = 0, the acceleration peaked or is constant. If so, a(t) is acceleration, da/dt=0 is a zero "jerk", the third derivative of displacement. > > IF da/dt > 0, the acceleration is increasing, so the object is gaining velocity (speed). It's ACCELERATING. If the acceleration (one dimensional physics definition) is already or has become positive, and the speed is also positive. Your "ACCELERATING" is the common usage of the word in this case. > > IF da/dt < 0, the acceleration is decreasing, so the object is losing velocity (speed). No, it loses velocity only if the acceleration is negative. The acceleration could switch from positive to negative if da/dt < 0, or it could still be positive after factoring in da/dt < 0 (for positive speed). Think of a car accelerating hard from a start (you floor it) but shortly you let off on the gas just a little, so it's still going faster and faster, just not as much. > It's DECELERATING, like in > the re-entry of a spacecraft. That's the common usage of the word, where the speed's absolute value decreases. Usually thought of as a positive speed and a negative value of acceleration. What of a car going in reverse and then the brakes are applied? Is the car accelerating, decelerating or something else? > >
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| From | "Dono." <eggy20011951@gmail.com> |
|---|---|
| Date | 2022-12-23 11:08 -0800 |
| Subject | Crank Dick Hertz fails classical kinemnatics |
| Message-ID | <7e037595-579e-40d3-b9c4-153800b74c84n@googlegroups.com> |
| In reply to | #598009 |
On Wednesday, December 21, 2022 at 4:52:00 PM UTC-8, Richard Hertz wrote: > IF da/dt < 0, the acceleration is decreasing, so the object is losing velocity (speed). Bzzt, fail.
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| From | Michelle Africano <nccr@amenica.he> |
|---|---|
| Date | 2022-12-21 23:25 +0000 |
| Message-ID | <to04lc$14snj$5@dont-email.me> |
| In reply to | #598004 |
Tom Roberts wrote: > On 12/21/22 2:52 PM, whodat wrote: >> [...] > > In common speech, "acceleration" means an increase in speed, and > "deceleration" means a decrease in speed. decrease in acceleration is decrease in speed. So *decrease_in_acceleration* is deceleration. A decrease in speed *is_just_still_acceleration* by your own definition, just the opposite direction.
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