Abstract: In this paper，nonlinear dynamic process of a physical pendulum system with big

swing angles is explored theoretically and experimentally. By considering the influence of the

friction and the air resistance，the de- cay process of the pendulum angle and the mechanical energy

with time is investigated with different initial angles and masses. By comparing with

the numerical simulation results，the friction coefficient of the rotation axis of the

physical pendulum and the air resistance coefficient are given as 0.025 and 0.68，respectively. The

results can pro- vide a reference for dynamic modeling of the pendulum structures such as bearing

and hinge.

Key words: physical pendulum, PASCO experimental system, coefficient of friction, coefficient of air resist-ance