Two blocks with mass m1,m2 connected by a spring with spring constant k2.
Drag "hand" in the simulation to push or pull the system (with spring k1) and watch how the system moves.
Click [url=]Usage link[/url] at the bottom of the simulation for illustration with flash movie.

VIEW or DOWNLOAD ejs xml source
then click to translate strings for selected locale.

Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop.