For a free spring, the wave velocity is v = √(k / m) x L, where L is the displacement of one end right? And what if I have a spring which both of its end is extended and held by "oscillator" to produce standing wave. In this case how would I find the wave velocity? I see some sources state that the equation i mentioned above is applicable. But wasn't L is the displacement? Or I did get the wrong idea about L ?