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MathGroup Archive 2000

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  • To: mathgroup at
  • Subject: [mg23718] Units
  • From: "Enrique Cao" <cao at>
  • Date: Mon, 5 Jun 2000 01:09:13 -0400 (EDT)
  • Sender: owner-wri-mathgroup at


I need help in order  to solve this problem.

I have the vector aceleration {3 t Meter/Second^2,t^2 Meter/Second^2}. 
This is a vector dependent of time (t).

I want to get the  position vector with initial conditions {x[0]==2 
Meter,y[0]==5 Meter,x'[1]==2 Meter/Second,y'[1]==3 

I do this with the follow  expression:

<< Miscellaneous`Units`

<< Miscellaneous`SIUnits`

DSolve[{x''[t]==3 t Meter/Second^2,y''[t]==t^2 Meter/Second^2, 
x[0]==2 Meter,y[0]==5 Meter,x'[1]==2 =
Meter/Second,y'[1]==3 Meter/Second },{x[t],y[t]},t]

The solution is

{x[t]->(Meter(4 Second^2+ 8 Second t +t^3 ))/(2 Second^2),

y[t]->Mter(3+(6 t)/Second+t^4/(12 Second^2))}

The unit of position is Meter but the  solution is not correct.

How can I get the correct solution ??

Thank you very much


cao at

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