Abstract: In this paper，the rotational motion of rigid body around a fixed axis is studied by

using Newton’s second law for rotation and in angular form with VPython software. Some

special examples discussed in detail are motions of rotating uniformly rod under different

torques，the path，angular displacement，angular velocity and mov- ing process，and were visualized

intuitively in real time. The conservation of the energy of rotating rigid rod only ex- perienced

with torque of gravity can be verified by VPython software. The plane motion of rigid

body ( translation plus rotation) and vibration of rigid body are also studied. Especially，the

chaos state of rigid rod with large rotating angle is investigated. The simulation deepens the

understanding of textbook knowledge.

Key words: torque, VPython, visualization, Newton’s second law for rotation, Newton’s second law in angu- lar form