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Conference rusure::math

Title:Mathematics at DEC
Moderator:RUSURE::EDP
Created:Mon Feb 03 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2083
Total number of notes:14613

1811.0. "help to solve equation" by PDV01::MEDONI () Fri Oct 29 1993 10:08

    hi all
    
    a friend of mine asked me to solve this differential equation:
    
    	  dv
      m * -- = m*g - k*v
          dt
    
    where   m = mass
    	    v = velocity
    	    g = the well known constant
    	    k = constant
    
    any help ... I need something like  v(t) = ....
    
    thanks
    Luciano
T.RTitleUserPersonal
Name		DateLines
1811.1HERON::BUCHANANThe was not found.Fri Oct 29 1993 10:3215
>    	   dv
>      m * -- = m*g - k*v
>          dt

	/ mdv    /
	|----- = | dt
	/mg-kv   /

Let u be the value of v at t=0, then:
   
	v = mg/k + (u-mg/k)*e^(-tk/m)

mg/k is the terminal velocity.

Andrew.
1811.2thanksPDV01::MEDONIFri Oct 29 1993 11:201