<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 12 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
h3
{mso-style-priority:9;
mso-style-link:"Heading 3 Char";
margin-top:10.0pt;
margin-right:0in;
margin-bottom:0in;
margin-left:0in;
margin-bottom:.0001pt;
page-break-after:avoid;
font-size:12.0pt;
font-family:"Cambria","serif";
color:#4F81BD;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma","sans-serif";}
span.hoenzb
{mso-style-name:hoenzb;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Arial","sans-serif";
color:windowtext;
font-weight:normal;
font-style:normal;}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma","sans-serif";}
span.Heading3Char
{mso-style-name:"Heading 3 Char";
mso-style-priority:9;
mso-style-link:"Heading 3";
font-family:"Cambria","serif";
color:#4F81BD;
font-weight:bold;}
.MsoChpDefault
{mso-style-type:export-only;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>The best bet is to ask the question at <a href="http://www.facebook.com/groups/RoboCommunity/">http://www.facebook.com/groups/RoboCommunity/</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>The guys that build bots with spinning disks will be able to answer questions related to rotational kinetic energy and provide the formulas. <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:black'>Rick Nickel<br>Owner,<br>Huntsville Computer Services<br>North Alabama Computer Services<br><a href="www.HuntsvilleComputer.com">www.HuntsvilleComputer.com</a><br>(256) 683-3003<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><o:p> </o:p></span></p><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> general-bounces@lists.makerslocal.org [mailto:general-bounces@lists.makerslocal.org] <b>On Behalf Of </b>Ethan Chew<br><b>Sent:</b> Wednesday, January 18, 2012 11:54 PM<br><b>To:</b> General discussion about makerslocal<br><b>Cc:</b> Eric Chew<br><b>Subject:</b> [General] Fwd: Drag torque<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Good Evening,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> I was wondering if you guys could help an inquiring young mind. Eric would like to know how to calculate the drag torque of a cylinder rotating on a shaft (wheel and axle configuration in picture attached). He will be applying a certain torque to rotate the assembly and is seeking a general equation that would tell him for the certain torque what the rotational velocity would be after a certain time, its maximum rotational velocity and how long it would take to reach it.<o:p></o:p></p></div><div><p class=MsoNormal> Help would be appreciated. Thanks!<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> - Ethan/spacefelix<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>---------- Forwarded message ----------<br>From: <b>Eric Chew</b> <<a href="mailto:ericchew24@gmail.com">ericchew24@gmail.com</a>><br>Date: Sat, Jan 14, 2012 at 8:44 PM<br>Subject: Re: Drag torque<br>To: Ethan Chew <<a href="mailto:spacefelix@gmail.com">spacefelix@gmail.com</a>><br><br><br>Hey! <br><br>So here's a simple picture of what I'm doing.<br><br>Pretty much, I'm trying to rotate a cylinder on an axle, as shown in the picture. I will be applying a certain torque on it, and I wanted to find a general equation that would tell me what the velocity would be after a certain time and also what the maximum velocity it could reach would be and how long it would take to reach it. <br><br>I talked with my physics teacher, and she told me that the equation I put on the paper would give me a general idea, but that calculating the drag torque would be difficult and that she didn't know how to. I tried looking on my own and found a lot of equations for drag force when something is moving, but nothing on when something is rotating in place. Do you know of an equation for the drag torque? Or could you help me derive one?<br><br>Thanks,<span style='color:#888888'><br><br><span class=hoenzb>Eric Chew</span></span><o:p></o:p></p><div><div><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>On Sat, Jan 14, 2012 at 4:49 PM, Ethan Chew <<a href="mailto:spacefelix@gmail.com" target="_blank">spacefelix@gmail.com</a>> wrote:<o:p></o:p></p><p class=MsoNormal>Hello!<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> This is my business/technical contact. Please use this e-mail only for technical and business communication. That being said, can you send me a drawing of your device and how it operates so I may understand how it is being loaded?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-bottom:12.0pt'> - Ethan<o:p></o:p></p><div><p class=MsoNormal>On Sat, Jan 14, 2012 at 1:44 PM, Ethan Chew <<a href="mailto:eflyingfelix@gmail.com" target="_blank">eflyingfelix@gmail.com</a>> wrote:<o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>---------- Forwarded message ----------<br>From: <b>Ethan Chew</b> <<a href="mailto:eflyingfelix@gmail.com" target="_blank">eflyingfelix@gmail.com</a>><br>Date: Sat, Jan 14, 2012 at 1:44 PM<br>Subject: Fwd: Drag torque<br>To: Ethan Chew <<a href="mailto:eflyingfelix@gmail.com" target="_blank">eflyingfelix@gmail.com</a>><o:p></o:p></p><div><div><p class=MsoNormal style='margin-bottom:12.0pt'><br><br><o:p></o:p></p><div><div><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>---------- Forwarded message ----------<br>From: <b>Eric Chew</b> <<a href="mailto:ericchew24@gmail.com" target="_blank">ericchew24@gmail.com</a>><br>Date: Sat, Jan 14, 2012 at 10:35 AM<br>Subject: Drag torque<br>To: Ethan Chew <<a href="mailto:eflyingfelix@gmail.com" target="_blank">eflyingfelix@gmail.com</a>><br><br><br>Hey Ethan,<br><br>I was wondering if you knew how to calculate the drag torque of a solid cylinder, given the radius, width, and mass of it, while it rotates on an axle in the air.<br><br>Thanks,<span style='color:#888888'><br><br>Eric Chew </span><o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div></div></div></div></div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p></div></div></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>