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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b>From:</b> spike@rainier66.com <spike@rainier66.com> <br><b>…</b><o:p></o:p></p></div></div><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>>…Usually the physics jockey hafta explain everything to us bonehead engineers, but we show them this, which appears to defy conservation of energy. It doesn’t, and it isn’t magic. We controls engineers have equations which deal with products of inertia and even have that icky coefficient of friction that physicists don’t like to deal with, all those distasteful non-linearities, swoon…. That isn’t what happens. More later if I get time. spike<o:p></o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>There is an experiment I have wanted to do for a long time but I live where the temperature hasn’t been cool enough for the past 24 years.<o:p></o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Get a container with enough water to create a perfectly smooth sheet of ice. Might need to leave it out, freezes, go over it with a cool iron (the kind we used to press a crease in trousers a looooong long time ago) creating a thin layer of water like a miniature Zamboni, let it re-freeze so you get a sheet of perfectly smooth ice. Then spin a tippee top on that. Demonstrate that without friction, it cannot get to its feet. Reasoning: to raise the CG, the spinning top has to borrow rotational energy and dump some of it in the process. Ah, got you there, say the physicists. Are you claiming rotational energy is lost to potential energy? No, reply the bonehead engineers. We know that angular momentum is conserved. A bit of the angular momentum from the tippee top goes into rotational energy of the planet. Without friction, the tippee top can’t dump that angular momentum and cannot get to its… foot.<o:p></o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Fun aside: those same equations explain why you have never seen a scaled-up tippee top. <o:p></o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Ja I know it is mind-boggling, but all the conservation laws still work: nothing failed.<o:p></o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>spike<o:p></o:p></span></pre></div></body></html>