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August 30th, 2017, 11:13 AM  #1 
Newbie Joined: Jul 2017 From: Iraq Posts: 18 Thanks: 0  massspring problem 1. The problem statement: Suppose at time zero, the bob was drawn upward four units from the equilibrium position, let C=2, K=2, m=1 lbm, initial speed=2 unit/sec find an expression for body's position. and in the solution it says: y''+6y'+5y=0 my question is: where do the numbers (6) and (5) that are in the above DE come from? 2. Relevant equations spring equation: my''+cy'+ky=f(t) consider f(t) =0 3. The attempt at a solution stopped at first because of the first step Last edited by skipjack; August 30th, 2017 at 01:55 PM. 
September 3rd, 2017, 04:45 AM  #2 
Math Team Joined: Jan 2015 From: Alabama Posts: 3,261 Thanks: 894  If, as you say, my''+ ky'+ Cy= 0 and you are given that C= 2, k= 5, and m= 1 then the equation should be y''+ 5y'+ 2y= 0 with initial condition y(0)= 4, y'(0)= 2.


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