Modeling Forced Oscillations with Viscous Damping and External Force

[qasbrv]

Homework Statement
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.

 

[Simon Bridge]

Don't you need the spring constant to find the natural frequency?
Is there any other information supplied? Maybe in the context?

 

[qasbrv]

Don't you need the spring constant to find the natural frequency?
Is there any other information supplied? Maybe in the context?

I thought that too, but that's all; nothing else given. Maybe the problem has some bugs.

 

[Simon Bridge]

Maybe ... ask.

 

[qasbrv]

I will
Thank you anyway!

 

[vela]

What do you suppose "a spring is stretched 2m by a mass of 2 kg" means?

 

[qasbrv]

It means that the maximum elongation x (amplitude) is exerted by the gravitational force =m*g ...so
-m*g=-kx
k=m*g/x= 10 N/m xD

Thank you very much!

 

[Simon Bridge]

Ooh... I missed it too, well done.

 

[rude man]

Poorly worded problem.
Is the mass subjected to the force 4cos (2t) directly, or is the force exerted on the mass indirectly by applying the force to a container containing the mass and viscous fluid? If the latter the mass of the fluid + containing vessel would also have to be specified.