Abstract: A new experimental method and system is used to measure the moment of inertia.The effect of string pull impacting on the friction torque of spindle is considered by adding a standard rigid body test piece in the physical experiment measuring the moment of inertia of a rigid body,which has improved the accuracy of this experiment greatly.In addition,the time data being measured by single MCU are transported to a personal computer by means of the communication network,which is according to PLT communication and TCP/IP protocol.Then the moment of inertia of the rigid body and other physical quantities are calculated by the data process software.Thisnew experiment method and system improves greatly the accuracy of the experiment and propitious to the communication between teacher and students and prevents students from plagiarizing each other.

Key words: measurement of moment of inertia, friction torque of spindle, standard rigid body test piece, PLT communication, TCP/IP protocol