#### tudur

I have quite a complex problem... I need to graph (on my PC, using excel or mathcad) the following motion:

a cube on a spring with given k and given initial Energy oscilates on a horizontal surface with friction coefficient u.

Now, i know this are damped oscillations which die out with time, but in order to graph them, i need to present the stopping force as b dx/dt , or as a fraction of the velocity...

what do i do? any ideas how to present friction through velocity, or am i completly on the wrong track??

thanx