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1、1/7 封面2/7 作者：PanHongliang 仅供个人学习第一节 机械功学案11【学习目标】理解功的概念。知道功是标量，认识正功、负功的含义，在具体的物理情景中能判断物体所受的各力是否做功以及做功的正负。能利用功的一般公式计算恒力的功，文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I
2、7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6
3、HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V
4、9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4
5、ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M
6、2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P1
7、0文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:
8、CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P103/7【学习重点】功的一般公式及其推导过程；判定物体所受的各个力是否做功以及做功的正负；总功的计算。【知识要点】1功功是力的空间积累效应。它和位移相对应（也和时间相对应）。计算功的方法：按照定义求功。即：W=Fscos。在高中阶段，这种方法只适用于恒力做功。当时 F 做正功，当时 F 不做功，当时 F 做负功。这种方法也可以说成是：功等于恒力和沿该恒力方向上的位移的乘积。2功的物理含义关于功我们不仅要从定义式W=Fs cos 进行理解和计算，还应理解它的物理含义功是能量转化的量度，即：做功的过程是能量的一个转化过程，这个
9、过程做了多少功，就有多少能量发生了转化对物体做正功，物体的能量增加做了多少正功，物体的能量就增加了多少；对物体做负功，也称物体克服阻力做功，物体的能量减少，做了多少负功，物体的能量就减少多少 因此功的正、负表示能的转化情况，表示物体是输入了能量还是输出了能量3一对作用力和反作用力做功的特点（1）一对作用力和反作用力在同一段时间内，可以都做正功、或者都做负功，或者一个做正功、一个做负功，或者都不做功。（2）一对作用力和反作用力在同一段时间内做的总功可能为正、可能为负、也可能为零。（3）一对互为作用反作用的摩擦力做的总功可能为零（静摩擦力）、可能为负（滑动摩擦力），但不可能为正。点评：一对作用力和
10、反作用力在同一段时间内的冲量一定大小相等，方向相反，矢量和为零。【典型例题】【例 1】用力将重物竖直提起，先是从静止开始匀加速上升，紧接着匀速上升。如果前后两过程的运动时间相同，不计空气阻力，则（）A加速过程中拉力做的功比匀速过程中拉力做的功大B匀速过程中拉力做的功比加速过程中拉力做的功大C两过程中拉力做的功一样大文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6
11、 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1
12、V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4
13、 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7
14、M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P
15、10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码
16、:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3
17、I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P104/7 D上述三种情况都有可能解读：应先分别求出两过程中拉力做的功，再进行比较。重物在竖直方向上仅受两个力作用，重力mg、拉力 F。匀加速提升重物时，设拉力为F1，物体向上的加速度为a，根据牛顿第二定律得 F1-mg=ma拉力 F1所做的功匀速提升重物时，设拉力为F2，根据平衡条件得F2=mg匀速运动的位移所以匀速提升重物时拉力的功比较、式知：当ag时，；当 a=g 时，；当 ag 时，故 D选项正确。【例 2】如图所示，均匀长直木板长L=40cm
18、，放在水平桌面上，它的右端与桌边相齐，木板质量m=2kg，与桌面间的摩擦因数=0.2，今用水平推力 F将其推下桌子，则水平推力至少做功为（）（g 取 10/s2）A0.8JB1.6JC8JD4J 解读：将木板推下桌子即木块的重心要通过桌子边缘，水平推力做的功至少等于克服滑动摩擦力做的功，J。故 A是正确的。【达标训练】1.质量为 m的物体，受水平力 F的作用，在粗糙的水平面上运动，下列说法中正确的是（）A如果物体做加速直线运动，F一定做正功B如果物体做减速直线运动，F一定做负功C如果物体做减速直线运动，F可能做正功D如果物体做匀速直线运动，F一定做正功2.关于力对物体做功，以下说法正确的是（）
19、A一对作用力和反作用力在相同时间内做的功一定大小相等，正负相反B不论怎样的力对物体做功，都可以用W=Fs cosC合外力对物体不作功，物体必定做匀速直线运动文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7
20、I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 H
21、S9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9
22、F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 Z
23、B8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2
24、D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10
25、文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P105/7 D滑
26、动摩擦力和静摩擦力都可以对物体做正功或负功3如图所示，某人用F100 的水平恒力，通过一质量和摩擦均不计的定滑轮把物体沿水平方向拉动了，则他对物体做的功为_J.4如图：用 F40 的水平推力推一个质量 31 kg 的木块，使其沿着斜面向上移动，木块和斜面间的动摩擦因数为0.1，则在这一过程中，F 做的功为 _J，物体克服摩擦力做的功为_J.重力做的功为 _J.（10/s25关于摩擦力做功的情况，下列说法中正确的是_.ABCD6下列几种情况下力F（）水平推力 F 推着质量为的物体在光滑水平面上前进了s水平推力 F 推着质量为的物体在粗糙水平面上前进了s沿倾角为 的光滑斜面的推力F将质量为 的物体
27、向上推了 s.下列说法中正确的是 _.A做功最多B做功最多C做功都相等D不能确定7起重机将质量为100 kg 的重物竖直向上移动了2，下列三种情况下，做功的力各有哪几个?每个力做了多少功?是正功还是负功?(不计阻力，9.8/s2)匀加速提高，加速度a0.2/s2匀速提高；匀减速下降，加速度大小a./s.答案：1解读：物体在粗糙水平面上运动，它必将受到滑动摩擦力，其方向和物体相对水平面的运动方向相反。当物体做加速运动时，其力 F方向必与物体运动方向夹锐角（含方向相同），这样才能使加速度方向与物体运动的方向相同。此时，力 F 与物体位移的方向夹锐角，所以，力F 对物体做正功，A 对。当物体做减速运
28、动时，力 F 的方向可以与物体的运动方向夹锐角也可以夹钝角（含方向相反），只要物体所受合力与物体运动方向相反即可，可见，物体做减速运动时，力 F 可能对物体做正功，也可能对物体做负功，B 错，C对。当物体做匀速运动时，力 F 的方向必与滑动摩擦力的方向相反，即与物体位文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P
29、10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码
30、:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3
31、I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6
32、 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1
33、V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4
34、 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7
35、M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P106/7 移方向相同，所以，力F 做正功，D对。故 A、C、D是正确的。2 解读：一对作用力和反作用力一定大小相等、方向相反，而相互作用的两物体所发生的位移不一定相等，它们所做的功不一定大小相等，所以，它们所做的功不一定大小相等，正负相反。公式W=Fs cos，只适用于恒力功的计算。合外力不做功，物体可以处于静止。滑动摩擦力、静摩擦力都可以做正功或负功.故 D是正确的。3.200 J4.64 J；9.6 J；36 J 5.BD6.C 7.拉力和重力；W拉2103J，W1.96103 J；拉力做正功
36、，重力做拉力和重力；均等于1.96103 J拉力和重力；拉力做功2103 J；重力做功 1.96 103 J；拉力做负功，重力做正功.【反思】收获疑问版权申明本文部分内容，包括文字、图片、以及设计等在网上搜集整理。版权为潘宏亮个人所有This article includes some parts,including text,pictures,and design.Copyright is Pan Hongliangs personal ownership.用户可将本文的内容或服务用于个人学习、研究或欣赏，以及其他非商业性或非盈利性用途，但同时应遵守著作权法及其他相关法律的规定，不得侵犯本网
37、站及相关权利人的合法权利。除此以外，将本文任何内容或服务用于其他用途时，须征得本人及相关权利人的书面许可，并支付报酬。文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB
38、8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D
39、10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文
40、档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK
41、7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I
42、3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS
43、9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P107/7 Users may use the con
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45、evant obligees.In addition,when any content or service of this article is used for other purposes,written permission and remuneration shall be obtained from the person concerned and the relevant obligee.转载或引用本文内容必须是以新闻性或资料性公共免费信息为使用目的的合理、善意引用，不得对本文内容原意进行曲解、修改，并自负版权等法律责任。Reproduction or quotation of
46、the content of this article must be reasonable and good-faith citation for the use of news or informative public free information.It shall not misinterpret or modify the original intention of the content of this article,and shall bear legal liability such as copyright.文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB
47、8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D
48、10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文
49、档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK
50、7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I3E6 HS9S1V9F8K4 ZB8N7M2D10P10文档编码:CK7G3I7I