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有些物理问题,若采用分解或合成力来解决,显得繁杂,如果转换思维角度,分解或合成加速度处理这类问题,能够达到“柳暗花明”的效果.现举几例.例1如图1所示,扶梯与水平面的夹角为30°,人的质量为m,当电梯斜向上以加速度a运动时,则扶梯对人的支持力和摩擦力各为多少?(已知当地的重力加速度为g)解析取人为研究对象,其受力如图2所示,将人的加速度分解到水平、竖直两个方向(如图3所示),由牛顿第二定律,在x方向有x:Ff=macos30°,y方向有:FN-mg=masin30°.解
Some physical problems, if the use of decomposition or synthesis to solve, it is complicated, if the conversion of thinking point of view, decomposition or synthetic acceleration of such problems, to achieve As shown, the angle between the escalator and the horizontal plane is 30 °, and the mass of the person is m. What is the support and friction for the escalator when the elevator is moving at the acceleration a in the diagonal direction? (It is known that the local gravitational acceleration G) Analyze the man-made object, the force shown in Figure 2, the human acceleration decomposition to the horizontal and vertical directions (as shown in Figure 3), by Newton’s second law in the x direction x : Ff = macos30 °, y direction: FN-mg = masin30 ° solution