On measurement of ”g” using a pair of a physical pendulum and a falling-body

A ”physical” pendulum executes to swing from its highest position. Simultaneously a weight is released from the axis of the swing. When this pendulum comes in the vertical, this freely falling body collides to the pendulum. From this fact, the acceleration of gravity ”g” is easily calculated as g=32 S/T2, where S is the distance from the swing axis to the point collided the falling-body, and T is the period of the pendulum. The valueof ”g” thus obtained empirically was about 10 m/s2. However, were the ”simple” pendulum employed instead of the ” physical ” one, the falling-body will not meet the pendulum, because of T=2π（L/g）1/2, where L is the length of the pendulum，and S＞￡.The discordance between experimental and theoretical requires to consider the concepts of the ”moment of inertia” and of the ”equivalent pendulum” and so on.