陀螺仪（车轮转台） 

       坐在转台上，一只手扶好方向盘另一只手转动右侧手柄，这时人和转台是静止的。当改变竖直方向时，奇怪的事出现了：人和转台转起来了而且转台转向始终和车轮转向相反。因为在竖直方向人体和车轮组成一个整体系统，没有外力矩作用时系统力求保持“静止”。车轮转动时，为保持系统的“静止”不被破坏，于是人和转台出现反向转动。力图保持整个系统“静止”，这就是角动量守衡定律。    

The Spinning Wheel and Revolving Seat

       First, the participant sits on the revolving seat. Then gripping the steering wheel with one hand, he begins to turn the spinning wheel with the other. While the axes of the spinning wheel and the revolving seat are perpendicular, the participant and the revolving stage are motionless. However, as soon as you move the spinning wheel from the vertical position by turning the steering wheel, the seat begins to rotate. It will always turn in the opposite direction to the movement of the steering wheel and will continue to rotate until the spinning wheel is returned to its original, vertical position. This is because the revolving seat is attempting to maintain the original inertia. This effort to always maintain inertia is known as ‘the angular momentum conservation law’.