So we have a mass spring system, which is supposed to be modelling a bridge, and the equation that the displacement of the bridge $x$ satisfies is given by $$M\ddot{x}+c\dot{x}+kx=0$$ where $M=4\times 10^5\text{kg}, c=5\times 10^4\text{kg/s}, k=10^7\text{kg} $, where $m$ is the mass, $k$ is the 'spring constant'and $c$ is the friction or level of damping or something, I'm not sure - this equation is pretty standard for this type of problem so you probably know what it means more than me anyway.
Now there is a part of the question where another factor is introduced, so that $x$ now satisfies the equation $$M\ddot{x}+c\dot{x}+kx=300\dot{N}.$$
Now my question is, is the damping level a constant value, so is it still $c$ or has it changed due to the new factor affecting $\dot{x}$ so would the damping now be $c-300N$? or does it just stay at $c$?
I think the main problem here is that I don't really know what is damping (what actually is damping )in general, so if anyone could just answer the question I asked above or say something about damping in general in these types of problems that would explain my confusion.