Phase

ü The quantity δ) is called the phase.

ü It determines the status of the particle in simple harmonic motion.

ü If the phase is zero at a certain instant, δ) = 0 and = A , which means that the particle is crossing the mean position and is going towards the positive direction.

ü If the phase is n/2, we get x = A, v = 0 so that the particle is at the positive extreme position.

Figure shows graphically the variation of position and velocity as a function of the phase.

Phase constant

ü The constant appearing in equation is called the phase constant.

ü This constant depends on the choice of the instant t = 0.

ü To describe the motion quantitatively, a particular instant should be called t = 0 and measurement of time should be made from this instant.

ü This instant may be chosen according to the convenience of the problem.