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View Full Version : [SOLVED] Lightly damped spring system Q


tjr39
Mar25-08, 07:16 PM
1. The problem statement, all variables and given/known data

Consider a lightly damped mass-on-a-spring vibrational system. How should motion be initiated so that the amplitude of the spring is given by;

\Psi(t)=Ce^{-\frac{\lambda}{2}t}Cos(\omega_{r}t+\pi)

2. Relevant equations



3. The attempt at a solution

I don't really know what is being asked "how should motion be initiated". Anyways I tried finding the solution at t=0,

\Psi(0)=Ce^{-\frac{\lambda}{2}*0}Cos(\omega_{r}*0+\pi)

Which simplifys to \Psi(0)=-C (as e^{0}=1 and Cos(\pi)=-1)

So is my answer just the spring should be stretched by aplitude C to give above equation of displacement? Thanks.

pam
Mar25-08, 08:33 PM
Also find the initial velocity by d\psi/dt.