一、分段求和法用公式W=Fscosθ求功时,s的大小有时等于路程.例1如图1所示,摆球的质量为m,悬线长为l,把悬线拉紧到水平位置A后放手,设在摆动过程中阻力f的大小不变.求摆球从A运动到竖直位置B的过程中阻力所做的功.解析阻力虽然大小不变,但方向不断改变,任何时刻都与运动方向相 First, the subsection summation method When the formula W = Fscosθ work, the size of s is sometimes equal to the distance. Example 1 As shown in Figure 1, the mass of the pendulum ball is m, the length of the suspension line is l, the suspension line is tightened to After the horizontal position A, let go, and set the magnitude of the resistance f in the course of swinging. Do the work done by the resistance in the process of swinging the ball from A to the vertical position B. Although the analytical resistance is constant, the direction changes continuously. At any moment with the direction of movement