A small sphere of mass m is attached to one end of a spring. Another end of the spring is fixed at point O. This applet simulate how the particle moves with different initial velocoty. (You can drag red arrow to change the velocity of the particle when the simulation is paused.)
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.