Method for measuring gravitational acceleration by utilizing increase of radius of pendulum bob

The invention provides a method for measuring the gravitational acceleration by utilizing increase of the radius of a pendulum bob. According to the method, a calculation formula of the gravitational acceleration g is obtained by analyzing the swinging period of a compound pendulum system consisting of a swinging rod and cylindrical weights, researching the change of the swinging period of the compound pendulum system when the radiuses of the cylindrical weights with the radiuses of r2 and r1 are gradually increased by step lengths of r2 and r1 and comparing the influences on the swinging period caused by different step lengths. Compared with the current experimental methods widely adopted, the method provided by the invention has the advantages that from the experimental principle, the equivalent pendulum length can be obtained without depending on changing the position of the compound pendulum system from a mass center to a suspension point, and the value of the gravitational acceleration obtained by the sl