From mechanics, you may recall that when the acceleration of an object is proportional to its coordinate,

From mechanics, you may recall that when the acceleration of an object is proportional to its coordinate, d2xdt2=âkmx=âÏ2x, such motion is called simple harmonic motion, and the coordinate depends on time as x(t)=acos(Ït+Ï), where Ï, the argument of the harmonic function at t=0, is called the phase constant.