论文部分内容阅读
当一个短跑运动员以常速率沿一条弯曲跑道赛跑是一种加速运动,其加速度指向曲线的中心。而运动员的身躯亦向加速度的方向倾斜以保持身体的平衡,其倾斜程度取决于加速的大小,该情况正如运动员在比賽开始离开起跑器时一样。因为赛跑运动员在弯道中是关于它本身的重心的旋转平衡(而不是平动平衡),因此,对于重心的转矩必然为零。所以,地面对脚的反作用力(在图1b中的F_R)必定通过人体的重心,而与重力的合力必定指向曲线的中心,且合力的大小为v~2/r。式中的v是运动员跑动的线速度,r是曲线的曲率半径,从图1b中能够看出: tanθ=V~2/rg或:V~2=grtan θ…(1)
When a sprinter runs at a constant speed along a curved track, it is an accelerating motion whose acceleration points to the center of the curve. The athlete’s body is also tilted in the direction of acceleration to maintain body balance, the degree of which depends on the size of the acceleration, just as the athlete does when starting the race. Because the runner in the curve is about the rotational balance of its own center of gravity (rather than the translational balance), the torque for the center of gravity must be zero. Therefore, the reaction of the ground to the foot (F_R in Figure 1b) must pass through the center of gravity of the human body while the resultant force with gravity must point to the center of the curve with a resultant force of v ~ 2 / r. Where v is the running speed of the athlete and r is the radius of curvature of the curve, as can be seen in Figure 1b: tanθ = V ~ 2 / rg or: V ~ 2 = grtan θ (1)