1. The problem statement, all variables and given/known data A rectangular cantilever beam of length L and side lengths b with negligible mass is attached horizontally to a wall. A mass m is attached to the end of the beam where a motor is also located. The motor applies a force on the end of the beam described by the equation P*sin(w*t). Derive an expression for the vertical vibration of the mass m, that is, find x(t) for a stable solution. 2. Relevant equations k = 3EI / L^3 I = b^4/12 3. The attempt at a solution I'm at a loss here. I am unaware of any equation that describes the damping in a cantilever beam. I want to set up the problem as x'' + c/m x' + k/m x = Psin(wt)/m which is how I usually solve these types of problems. But I'm at a loss when it comes to finding out how to express c. Furthermore, when it says to find a stable solution, is it hinting towards harmonic motion?