关键词: 单摆, 重力加速度, 摆线, 摆长改变量, 角振幅

Abstract: In the experiment of measuring the gravity acceleration by a single pendulum，it is difficult to determine

the pendulum length very accurately. Under the better measurement conditions，the measurement accuracy

could generally reach the order of millimeter，and the relative error of the measured gravity acceleration is generally

about 1%. In order to solve this problem，in this paper the measuring precision was improved to 0.02mm by using

avernier caliper connected with a cycloid to accurately measure the change of pendulum length instead of directly

measuring the pendulum length. At the same time，the swing period of the pendulum ball is measured by a photoelectric

gate，and the different cycloid material and diameter are compared and analyzed.The measurement error of

acceleration is controlled within 0.1%.

Key words: single pendulum, gravity acceleration, cycloid, change of pendulum length, angular amplitude