论文部分内容阅读
众所周知,作匀速圆周运动的物体的向心力就是物体所受的合外力。如图1,在匀速转动的圆枱上,放一物体M,两者保持相对静止。物体维持匀速圆周运动所需的向心力就是物体与枱面间的静摩擦力f。如果物体与枱面间的静摩擦力不足以提供物体随圆枱作匀速圆周运动的向心力,物体M将沿切线方向向前运动。而在有关摩擦力的阐述中指出:“静摩擦力的方向跟物体间的相对运动趋势相反。”因此有学生就提出:“既然当物体与枱面间的摩擦力不足时,物体M将沿切线方向向前运动,静摩擦力的方向就应沿切线方向向后,这与由静摩擦力提供向心力不是互相矛盾吗?”物体与枱
As we all know, the centripetal force of an object that makes a circular motion in a uniform speed is the external force applied to the object. As shown in Fig. 1, on a circular table that rotates at a constant speed, an object M is placed and the two remain relatively stationary. The centripetal force required to maintain a constant circular motion of an object is the static friction force f between the object and the table. If the static friction force between the object and the table is not enough to provide the centripetal force for the object to move in a uniform circle with the circular table, the object M will move forward along the tangential direction. In the description of frictional forces, it is pointed out that: “The direction of static friction force is opposite to the relative movement of objects.” Therefore, some students put forward: “Since the friction between the object and the table is insufficient, the object M will Moving forward in a tangential direction, the direction of the static friction should be tangentially backward. Is this not inconsistent with the centripetal force provided by the static friction?”Objects and tables