What is the Differential Equation for This Mechanical System?

[gjfelix2001]

Homework Statement

In this problem I'm asked to give the differential equation of the mechanical system in the following diagram:

http://www.jelp.org/imagenes/mech.jpg

Homework Equations

Once i understand the diagram, i'll get the motion equation by Newton or lagrange. But what is G in the diagram?? I can't ask to the "creator of the draw". Is the black dot fixed? What do you think?? Thanks a lot...

 

[jambaugh]

The "squggle" is a spring with spring constant K, the box is a mass. The open box G is a "dash pot" or dampener with dampening constant G (applies a force -G times the velocity) and of course the wall on the right is a wall i.e. fixed point.

I'm not sure about the f(t), whether that is a force or a position x1=f(t). My guess is that it is indeed a force.