Originally Posted by

**moolimanj** Hi all.

I have got the following question regarding a seismograph and what I would like to do is to express the forces acting on the particle in terms of the given variables and parameters and the unit vector i. Can some one please help?

Is there any way I can express the displacement vector P of the mass relative to the origin 0 in terms of x,y, d and i. If there is, what would the equation of motion of the particle look like and how can I show that x(t) satisfies the differential equation

md^2x/dt^2 +rdx/dt+kx=mg+kl+md^2y/dt^2