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MathGroup Archive 2001

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Re: Deriviation d/dt(x(t))

  • To: mathgroup at smc.vnet.net
  • Subject: [mg27465] Re: Deriviation d/dt(x(t))
  • From: "Kevin J. McCann" <KevinMcCann at home.com>
  • Date: Tue, 27 Feb 2001 00:37:18 -0500 (EST)
  • References: <97a6up$akb@smc.vnet.net> <R7mm6.17731$0r1.43554@ralph.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

circle = x^2 + y^2 ==r^2
SetAttributes[r,Constant]

Dt[circle]

> 2 x Dt[x,t] + 2 y Dt[y,t]==0

Kevin

The wise words of DennisW555 on Mon, 26 Feb 2001 05:49:37 GMT:

> >I have a problem, having a definition of a circle: x^2+y^2=r^2
> >Where x and y are functions of the time:  x(t), y(t) and r ist a
> >constant.
> >
> >Now I want to deriviate the equation to get the velocity vector.
> >It should be : 2 x dx/dt +2 y dy/dt = 0
> 
> The velocity vector is simply {dx/dt, dydt}
> 
> 



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