Vargason, Richard Period 4 As the mass on the end of the pendulum increases, the period stays constant, showing that there is no relation between mass and period of a pendulum system. As the length of the pendulum string increases, the period increases with it, showing that there is a direct relation between length and period of a pendulum system. Vargason, Richard Period 4 As the amplitude of the pendulum system increases, the period stays constant, showing that there is no relation between amplitude and period of a pendulum system.