Re: defining laws in isolation or 'no other force acting'
Gary Oberbrunner <[email protected]> Fri, 31 Jan 2014 06:01:16 -0500
| Newsgroups | gmane.science.physics.fabric-of-reality |
|---|---|
| Message-ID | <CAFChFyhoUjwyJAag8V6tENcX8HaOufWP2ER4iCRYbYNZrFPUyA@mail.gmail.com> |
--A2zbEXODXeb-Rs13PM2S392yRE24Oa3kSTCqSwK Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit On Wed, Jan 22, 2014 at 12:08 AM, <hibbsa-/[email protected]> wrote: > > > > > ---In [email protected], <garyo@...> wrote: > > > On Sun, Jan 19, 2014 at 2:26 AM, <hibbsa@...> wrote: > >>> the reasoning seems to reverse quite easily, such that the second law >>> derives from the first. >> >> >> The first law doesn't specify the relationship between force and >> acceleration (except that there is one). For instance, F=m*a^2 would also >> lead to bodies at rest staying at rest and bodies in motion staying in that >> state of motion. (There's no acceleration in either case.) So you can't >> derive the second law from the first, only the other way. >> >> -- >> Gary > > You might be tempted to kick yourself when you your brain realizes it's > true before I can finish writing that "you got the problem right but the > wrong context" as "F -> a" is the right relationship, but the way it could > be in terms of "a" is the trivial context, and "m" is the intractable > problem. > > But there's a reason why you couldn't choose "m" even though "F -> a" , is > literally substituting "m" for "->" (i.e. relationship) in a context that > you've probably known since you were about 8. > > But the intractability of "m" is that in the history of the end to end > reasoning, "m" never existed, and there was never a way to bring it into > existence. > > Sorry, I have absolutely no idea what you're talking about here. -- Gary --A2zbEXODXeb-Rs13PM2S392yRE24Oa3kSTCqSwK Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> </head> <body style="background-color: #fff;"> <span style="display:none"> </span> <!--~-|**|PrettyHtmlStartT|**|-~--> <div id="ygrp-mlmsg" style="position:relative;"> <div id="ygrp-msg" style="z-index: 1;"> <!--~-|**|PrettyHtmlEndT|**|-~--> <div id="ygrp-text" > <p>On Wed, Jan 22, 2014 at 12:08 AM, <hibbsa-/[email protected]> wrote:<br> <br> ><br> ><br> ><br> ><br> > ---In [email protected], <garyo@...> wrote:<br> ><br> ><br> > On Sun, Jan 19, 2014 at 2:26 AM, <hibbsa@...> wrote:<br> ><br> >>> the reasoning seems to reverse quite easily, such that the second law<br> >>> derives from the first.<br> >><br> >><br> >> The first law doesn't specify the relationship between force and<br> >> acceleration (except that there is one). For instance, F=m*a^2 would also<br> >> lead to bodies at rest staying at rest and bodies in motion staying in that<br> >> state of motion. (There's no acceleration in either case.) So you can't<br> >> derive the second law from the first, only the other way.<br> >><br> >> --<br> >> Gary<br> ><br> > You might be tempted to kick yourself when you your brain realizes it's<br> > true before I can finish writing that "you got the problem right but the<br> > wrong context" as "F -> a" is the right relationship, but the way it could<br> > be in terms of "a" is the trivial context, and "m" is the intractable<br> > problem.<br> ><br> > But there's a reason why you couldn't choose "m" even though "F -> a" , is<br> > literally substituting "m" for "->" (i.e. relationship) in a context that<br> > you've probably known since you were about 8.<br> ><br> > But the intractability of "m" is that in the history of the end to end<br> > reasoning, "m" never existed, and there was never a way to bring it into<br> > existence.<br> ><br> ><br> Sorry, I have absolutely no idea what you're talking about here.<br> <br> -- <br> Gary<br> <br> </p> </div> <!--~-|**|PrettyHtmlStart|**|-~--> <div style="color: #fff; height: 0;">__._,_.___</div> <div style="clear:both"> </div> <table cellspacing=4px style="margin-top: 20px; margin-bottom: 10px;"> <tbody> <tr> <td style="font-size: 12px; font-family: arial; font-weight: bold; padding: 7px 5px 5px; color: #FFF; background-color: #F2F2F2; border: 1px solid #EAEAEA " > <a style="text-decoration: none; color: #2D50FD" href="http://groups.yahoo.com/group/Fabric-of-Reality/post;_ylc=X3oDMTJxYmwzdnBnBF9TAzk3MzU5NzE0BGdycElkAzE4ODg2MDAEZ3Jwc3BJZAMxNzA1MDIwNTg1BG1zZ0lkAzI1NjI3BHNlYwNmdHIEc2xrA3JwbHkEc3RpbWUDMTM5MTUwMzM2OA--?act=reply&messageNum=25627">Reply via web post</a> </td> <td style="font-size: 12px; font-family: arial; padding: 7px 5px 5px; color: #FFF; background-color: #F2F2F2; border: 1px solid #EAEAEA; " > <a href="mailto:[email protected]?subject=Re%3A%20defining%20laws%20in%20isolation%20or%20%27no%20other%20force%20acting%27" style="text-decoration: none; color: #2D50FD;"> Reply to sender </a> </td> <td style="font-size: 12px; font-family: arial; padding: 7px 5px 5px; color: #FFF; background-color: #F2F2F2; border: 1px solid #EAEAEA; "> <a href="mailto:[email protected]?subject=Re%3A%20defining%20laws%20in%20isolation%20or%20%27no%20other%20force%20acting%27" style="text-decoration: none; color: #2D50FD"> Reply to group </a> </td> <td style="font-size: 12px; font-family: arial; padding: 7px 5px 5px; color: #FFF; background-color: #F2F2F2; border: 1px solid #EAEAEA; " > <a href="http://groups.yahoo.com/group/Fabric-of-Reality/post;_ylc=X3oDMTJlczQ3bjc0BF9TAzk3MzU5NzE0BGdycElkAzE4ODg2MDAEZ3Jwc3BJZAMxNzA1MDIwNTg1BHNlYwNmdHIEc2xrA250cGMEc3RpbWUDMTM5MTUwMzM2OA--" style="text-decoration: none; color: #2D50FD">Start a New Topic</a> </td> <td style="font-size: 12px; font-family: arial; padding: 7px 5px 5px; color: #2D50FD; background-color: #F2F2F2; border: 1px solid #EAEAEA; " > <a href="http://groups.yahoo.com/group/Fabric-of-Reality/message/25606;_ylc=X3oDMTM2Nm4ycHNtBF9TAzk3MzU5NzE0BGdycElkAzE4ODg2MDAEZ3Jwc3BJZAMxNzA1MDIwNTg1BG1zZ0lkAzI1NjI3BHNlYwNmdHIEc2xrA3Z0cGMEc3RpbWUDMTM5MTUwMzM2OAR0cGNJZAMyNTYwNg--" style="text-decoration: none; color: #2D50FD;">Messages in this topic</a> (11) </td> </tr> </tbody> </table> <!------- Start Nav Bar ------> <!-- |**|begin egp html banner|**| --> <div id="ygrp-vital" style="background-color: #f2f2f2; font-family: Verdana; font-size: 10px; margin-bottom: 10px; padding: 10px;"> <span id="vithd" style="font-weight: bold; color: #333; text-transform: uppercase; "><a href="http://groups.yahoo.com/group/Fabric-of-Reality;_ylc=X3oDMTJldWJrOTlzBF9TAzk3MzU5NzE0BGdycElkAzE4ODg2MDAEZ3Jwc3BJZAMxNzA1MDIwNTg1BHNlYwN2dGwEc2xrA3ZnaHAEc3RpbWUDMTM5MTUwMzM2OA--" style="text-decoration: none;">Visit Your Group</a></span> <ul style="list-style-type: none; margin: 0; padding: 0; display: inline;"> </ul> </div> <div id="ft" style="font-family: Arial; font-size: 11px; margin-top: 5px; padding: 0 2px 0 0; clear: both;"> <a href="http://groups.yahoo.com/;_ylc=X3oDMTJkbnVidDZ2BF9TAzk3MzU5NzE0BGdycElkAzE4ODg2MDAEZ3Jwc3BJZAMxNzA1MDIwNTg1BHNlYwNmdHIEc2xrA2dmcARzdGltZQMxMzkxNTAzMzY4" style="float: left;"><img src="http://l.yimg.com/ru/static/images/yg/img/email/new_logo/logo-groups-137x15.png" height="15" width="137" alt="Yahoo! Groups" style="border: 0;"/></a> <div style="color: #747575; float: right;"> • <a href="http://info.yahoo.com/privacy/us/yahoo/groups/details.html" style="text-decoration: none;">Privacy</a> • <a href="mailto:Fabric-of-Reality-unsubscribe-hHKSG33TihhbjbujkaE4pw@public.gmane.org?subject=Unsubscribe" style="text-decoration: none;">Unsubscribe</a> • <a href="http://info.yahoo.com/legal/us/yahoo/utos/terms/" style="text-decoration: none;">Terms of Use</a> </div> </div> <!-- |**|end egp html banner|**| --> </div> <!-- ygrp-msg --> <!-- Sponsor --> <!-- |**|begin egp html banner|**| --> <div id="ygrp-sponsor" style="width:160px; float:right; clear:none; margin:0 0 25px 0; background: #fff;"> <!-- Start Recommendations --> <div id="ygrp-reco"> </div> <!-- End Recommendations --> </div> <!-- |**|end egp html banner|**| --> <div style="clear:both; color: #FFF; font-size:1px;">.</div> </div> <img src="http://geo.yahoo.com/serv?s=97359714/grpId=1888600/grpspId=1705020585/msgId=25627/stime=1391503368" width="1" height="1"> <br> <div style="color: #fff; height: 0;">__,_._,___</div> <!--~-|**|PrettyHtmlEnd|**|-~--> </body> <!--~-|**|PrettyHtmlStart|**|-~--> <head> <style type="text/css"> <!-- #ygrp-mkp { border: 1px solid #d8d8d8; font-family: Arial; margin: 10px 0; padding: 0 10px; } #ygrp-mkp hr { border: 1px solid #d8d8d8; } #ygrp-mkp #hd { color: #628c2a; font-size: 85%; font-weight: 700; line-height: 122%; margin: 10px 0; } #ygrp-mkp #ads { margin-bottom: 10px; } #ygrp-mkp .ad { padding: 0 0; } #ygrp-mkp .ad p { margin: 0; } #ygrp-mkp .ad a { color: #0000ff; text-decoration: none; } #ygrp-sponsor #ygrp-lc { font-family: Arial; } #ygrp-sponsor #ygrp-lc #hd { margin: 10px 0px; font-weight: 700; font-size: 78%; line-height: 122%; } #ygrp-sponsor #ygrp-lc .ad { margin-bottom: 10px; padding: 0 0; } #actions { font-family: Verdana; font-size: 11px; padding: 10px 0; } #activity { background-color: #e0ecee; float: left; font-family: Verdana; font-size: 10px; padding: 10px; } #activity span { font-weight: 700; } #activity span:first-child { text-transform: uppercase; } #activity span a { color: #5085b6; text-decoration: none; } #activity span span { color: #ff7900; } #activity span .underline { text-decoration: underline; } .attach { clear: both; display: table; font-family: Arial; font-size: 12px; padding: 10px 0; width: 400px; } .attach div a { text-decoration: none; } .attach img { border: none; padding-right: 5px; } .attach label { display: block; margin-bottom: 5px; } .attach label a { text-decoration: none; } blockquote { margin: 0 0 0 4px; } .bold { font-family: Arial; font-size: 13px; font-weight: 700; } .bold a { text-decoration: none; } dd.last p a { font-family: Verdana; font-weight: 700; } dd.last p span { margin-right: 10px; font-family: Verdana; font-weight: 700; } dd.last p span.yshortcuts { margin-right: 0; } div.attach-table div div a { text-decoration: none; } div.attach-table { width: 400px; } div.file-title a, div.file-title a:active, div.file-title a:hover, div.file-title a:visited { text-decoration: none; } div.photo-title a, div.photo-title a:active, div.photo-title a:hover, div.photo-title a:visited { text-decoration: none; } div#ygrp-mlmsg #ygrp-msg p a span.yshortcuts { font-family: Verdana; font-size: 10px; font-weight: normal; } .green { color: #628c2a; } .MsoNormal { margin: 0 0 0 0; } o { font-size: 0; } #photos div { float: left; width: 72px; } #photos div div { border: 1px solid #666666; height: 62px; overflow: hidden; width: 62px; } #photos div label { color: #666666; font-size: 10px; overflow: hidden; text-align: center; white-space: nowrap; width: 64px; } #reco-category { font-size: 77%; } #reco-desc { font-size: 77%; } .replbq { margin: 4px; } #ygrp-actbar div a:first-child { /* border-right: 0px solid #000;*/ margin-right: 2px; padding-right: 5px; } #ygrp-mlmsg { font-size: 13px; font-family: Arial, helvetica,clean, sans-serif; *font-size: small; *font: x-small; } #ygrp-mlmsg table { font-size: inherit; font: 100%; } #ygrp-mlmsg select, input, textarea { font: 99% Arial, Helvetica, clean, sans-serif; } #ygrp-mlmsg pre, code { font:115% monospace; *font-size:100%; } #ygrp-mlmsg * { line-height: 1.22em; } #ygrp-mlmsg #logo { padding-bottom: 10px; } #ygrp-msg p a { font-family: Verdana; } #ygrp-msg p#attach-count span { color: #1E66AE; font-weight: 700; } #ygrp-reco #reco-head { color: #ff7900; font-weight: 700; } #ygrp-reco { margin-bottom: 20px; padding: 0px; } #ygrp-sponsor #ov li a { font-size: 130%; text-decoration: none; } #ygrp-sponsor #ov li { font-size: 77%; list-style-type: square; padding: 6px 0; } #ygrp-sponsor #ov ul { margin: 0; padding: 0 0 0 8px; } #ygrp-text { font-family: Georgia; } #ygrp-text p { margin: 0 0 1em 0; } #ygrp-text tt { font-size: 120%; } #ygrp-vital ul li:last-child { border-right: none !important; } --> </style> </head> <!--~-|**|PrettyHtmlEnd|**|-~--> </html> <!-- end group email --> --A2zbEXODXeb-Rs13PM2S392yRE24Oa3kSTCqSwK--