Statics G
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功学 G 12
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Statics 3)CharacteristicS: Magnitude: 0< F< F(range of equilibrium and >x=0 should be satisfied Characteristics Direction: oppose to the relative motion of the of the staticbodies force of friction: Law: Fmax=f. N depends only on the materials and the surface conditions, it does not depend on the area of the sur face of contact) 2. Slipping force of friction: the difference with static one is that motion has occurred) Magnitude: F=fN(without equilibrium range) Characteristics of the slipping Direction: opposite to the motion force of friction: Law:F'=fN("only depends on the materials and the sur face conditions, it does not depend on the area of the surface of contact 13
13 0 F Fmax X = 0 Fmax = f N 3)Characteristics: Magnitude: (range of equilibrium) and should be satisfied. Characteristics Direction: oppose to the relative motion of the of the static bodies. force of friction: Law: (f depends only on the materials and the surface conditions, it does not depend on the area of the surface of contact). 2. Slipping force of friction: (the difference with static one is that motion has occurred) Magnitude: (without equilibrium range) Characteristics of the slipping Direction: opposite to the motion. force of friction: Law: (f‘ only depends on the materials and the surface conditions, it does not depend on the area of the surface of contact). F' = f ' N F' = f ' N
功学 3、特征:大小:0≤F≤Fm(平衡范围)满足∑X=0 静摩擦力特征方向:与物体相对滑动趋势方向相反 定律:F=fN(∫只与材料和表面情况有 关,与接触面积大小无关。) 二、动滑动摩擦力:(与静滑动摩擦力不同的是产生了滑动) 大小:F"=f·N (无平衡范围) 动摩擦力特征:方向:与物体运动方向相反 定律:F=N(只与材料和表面情况有 关,与接触面积大小无关。) 14
14 二、动滑动摩擦力：（与静滑动摩擦力不同的是产生了滑动） 大小： （无平衡范围） 动摩擦力特征：方向：与物体运动方向相反 定律： （f '只与材料和表面情况有 关，与接触面积大小无关。） 0 F Fmax X = 0 Fmax = f N F' = f ' N F' = f ' N 3、 特征： 大小： （平衡范围）满足 静摩擦力特征：方向：与物体相对滑动趋势方向相反 定律： （ f 只与材料和表面情况有 关，与接触面积大小无关。）
Statics 3. Angle of friction: ① Concept: If the magnitude of the static force of friction increases from zero to the maximu lum value Fmax the maximum angle mwhich the total reaction of a rough support makes with the normal to the surface is called the angle of friction o n ② Calculation N mNN f N Rm (Look for the animation on the next page) 15
15 f N f N N F m = = = max tg ②Calculation: m 3. Angle of friction: ①Concept: If the magnitude of the static force of friction increases from zero to the maximum value , the maximum angle which the total reaction of a rough support makes with the normal to the surface is called the angle of friction. Fmax (Look for the animation on the next page)