1. The problem statement, all variables and given/known data What is the phase constant (from 0 to 2π rad) for the harmonic oscillator with the velocity function v(t) given in Fig. 15-30 if the position function x(t) has the form x = xmcos(ωt + φ)? The vertical axis scale is set by vs = 7.50 cm/s. [PLAIN]http://img227.imageshack.us/img227/4729/qu1512.gif [Broken] 2. Relevant equations x = xmcos(ωt + φ) v=-ωxmsin(ωt + φ) vm=ωxm 3. The attempt at a solution From graph, vm=9.375 cm/s vm=9.375 cm/s = ωxm xm=9.375/ω At t=0, v(0)=7.5 cm/s=-ωxmsin(φ) φ=sin-1(7.5/-ωxm) φ=sin-1(7.5/-ω*9.375/ω) φ=sin-1(7.5/-9.375)= -.927 rad I still got it wrong and not sure where I messed up. Only thing that I can think of is that I incorrectly assumed t=0 is 7.5 cm/s and if that's the case then I don't know where to begin on this problem.