Influence of the Number of Cycles to the Gravity Acceleration Measured by Three Line Pendulum

The three wire pendulum method was used to deduce the rotary inertia of the three wire pendulum. Furthermore, the principle was used to deduce the expression of acceleration of gravity. In order to improve the accuracy of gravity acceleration in Harbin area by three wire pendulum method, the rotation period number is 5, 10, 20, 40, 30 and 50, respectively. The impact of the air resistance and friction between suspension lines to acceleration of gravity was analyzed by choosing different the number of rotation period. According to the compare between the Haerbin gravity acceleration of experiment and Haerbin gravity acceleration of reasonable, the optimal numbers of rotation period is 40.