It depends on the choice of the instant t = 0. Phase Angle (ф) The time varying quantity (ωt +ф) is called the phase of the motion and the quantity ф is called the phase angle or phase constant. It is the maximum displacement of the particle from the center of oscillation i.e. This gives the physical significance of the constant A. As sin(ωt +ф) can take values between -1 and +1, the displacement x can take values between –A and +A. Amplitude The quantity A is called the amplitude of the motion.
