[SOLVED] Simple Harmonic Oscillator 1. The problem statement, all variables and given/known data The equation of motion of a simple harmonic oscillator is (second derivative of x wrt t) d2x/dt2 = -9x, where x is displacement and t is time. The period of oscillation is? 2. Relevant equations 2 pi f = omega f = 1/T 3. The attempt at a solution Given the relevant equations, one can show that omega / 2pi = f 2pi/omega = T The answer is 2pi/3 by the way, and I have trouble getting to this number. I probably have to integrate something, but I don't know what that would buy me. dx/dt = -9/2 x^2 and x = -3/2 x^3. When x is sinusoidal, I know the general form of the equation, but I am totally lost here.