Re: need help determined time to travel a path

• To: mathgroup at smc.vnet.net
• Subject: [mg107544] Re: [mg107512] need help determined time to travel a path
• From: Brad Walker <bwalker at musings.com>
• Date: Tue, 16 Feb 2010 03:54:37 -0500 (EST)
• References: <201002151047.FAA28291@smc.vnet.net>

g = 9.81 and time0 = 0

Yea, I guess pi should be capitalized. But, this is what happens when
one cuts and paste and it's 11:30 pm..

Thanks for any help.

On Mon, Feb 15, 2010 at 10:16 AM, Tomas Garza <tgarza10 at msn.com> wrote:
> What is g? What is time0? Also, pi should be capitalized (pi).
>
> Tomas
>
>> Date: Mon, 15 Feb 2010 05:47:53 -0500
>> Subject: [mg107512] need help determined time to travel a path
>> To: mathgroup at smc.vnet.net
>>
>> I am trying to determine the time to travel a circular path. This path is
>> on a
>> circle. It's fairly easy to understand.
>>
>> But, I can't seem to figure out why this is failing.
>>
>> (* define my parametrizations *)
>> circlex[t_]:=13+13*Sin[t+pi];
>> circley[t_]:=13+13*Cos[t+pi];
>>
>> (* the derivatives *)
>> dcirx[t_]:=D[circlex[t],t];
>> dciry[t_]:=D[circley[t],t];
>>
>>
>> (* amount of time needed to travel a circle *)
>> Integrate[Sqrt[(dcirx[t])^2+(dciry[t])^2]/Sqrt[2*g*(circley[time0]-
>> circley[t])], {t, 0.01, pi/2}]
>>
>> I get a negative value for the time. This can't be right..
>>
>> Any help is much appreciated!!
>>
>> Thanks.
>>