# Homework Help: Damped harmonic oscillator being forced

1. Jun 26, 2011

### tomwilliam

1. The problem statement, all variables and given/known data

A damped harmonic oscillator is being forced. I have to say whether it is direct forcing or forcing by displacement. I have the equation of motion which is expressed in terms of the particle's height above the equilibrium point and an expression for the force being applied.

2. Relevant equations

3. The attempt at a solution
I know that if it is forcing by displacement there should be a change in the length of the spring to which the particle is attached, but as my equation of motion is in terms of height above the equilibrium point, I'm not sure I can tell whether the spring length is constant or not. The forcing element is of the form C cos (omega t). I'm not sure whether I should be showing my answer to this question using a mathematical argument or based on the physical set up. Any help appreciated.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution