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## Homework Statement

I have a damped forced vibration problem. Most problems I have dealt with have a constant amplitude sinusoidal force such as F_0sin(wt). Let's say you have an applied force that decreases each second at a constant rate over 11 seconds. It looks like this:

F=0.5*[(11-t)sin(2*pi*t)+(11-t)]; (0<= t >=11)

The graph of this force has been attached.

## Homework Equations

The system is also critically damped so the system's differential equation is:

m[d^2/dt^2](x) + c(dx/dt) +kx = 0.5*[(11-t)sin(2*pi*t)+(11-t)]

## The Attempt at a Solution

From here I'm not too sure how to proceed. Normally with forced vibration the solution would include both a complimentary and particlular soluntion since it is a nonhomogenous linear second order differential equation. So

x = x_c + x_p

If the force had a constant magnitude (steady state vibration) and assuming critical damping x_c would look like:

x_c=(A+B*t)e^(-W_n*t)

but since the vibration is not steady state does this equation hold true? I assume it does only because the complimentary solution is found by setting the force to zero and assuming only free vibration. A and B are then found using the initial conditions where:

A= x_c(0) or is it A=x(0)

B=Dx(0)/dt + w_n*x(0)

Then x_p needs to be found and this I am having trouble with. how would one solve this part of the differential?