The problem statement, all variables and given/known data A spring is stretched 2m by a mass of 2 kg. The body is immersed in a viscous fluid with the damping coefficient having 4 Ns / m which is driven by an external force 4cos (2t). Plot mass position versus time. g = 10 m / s2. The attempt at a solution I know first I have to find an equivalent form as that of forced oscilations x⋅⋅+2γx⋅+ω02x = F×cos(ωt)/m but I can't figure out because I don't have an elasticity const k or a frequency. I think I don't need one, but I don't know how to start.