在讲汽车的牵引力就是后轮(驱动轮)所受地面对它的静摩擦力时,学生感到难以理解。分析汽车前、后轮所受静摩擦力的方向,学生也甚感困难。有的学生甚至对汽车的车轮受到的是地面对它的静摩擦力也感到怀凝。为此,我设计了一个钢丝轮小车,其结构如图1中(a)、(b)、(c)、(d)所示。 When the traction of a car is the static friction of the rear wheel (driving wheel), students find it difficult to understand. Analysing the direction of static friction in the front and rear wheels of the car is also very difficult for students. Some students even feel the wrinkle of the car’s wheels being ground against it’s static friction. For this purpose, I designed a wire wheel trolley whose structure is shown in (a), (b), (c), (d) of Figure 1.