题目内容
(9分)现要测定木块与长木板之间的动摩擦因数,给定的器材如下:一个倾角可以调节的长木板(如图)、木块、计时器、米尺。请填入适当的公式或文字,完善以下实验步骤:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025544311523.png)
①用米尺测量长木板顶端B相对于水平桌面CA的高度
和长木板的总长度
.设木块所受重力为
,木块与长木板之间的动摩擦因数为
,则木块所受的合外力表达式
=_____________.
②让木块从斜面上方一固定点D由静止开始下滑到斜面底端A处,记下所用的时间
,用米尺测量D与A之间的距离
.
③根据牛顿第二定律,可求得动摩擦因数的表达式
=__________,代入测量值计算求出
的值.
④改变______________________________,重复上述测量和计算;再求出
的平均值.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025544311523.png)
①用米尺测量长木板顶端B相对于水平桌面CA的高度
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554447313.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554462280.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554493414.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554509301.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554525302.png)
②让木块从斜面上方一固定点D由静止开始下滑到斜面底端A处,记下所用的时间
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554556267.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554571258.png)
③根据牛顿第二定律,可求得动摩擦因数的表达式
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554509301.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554509301.png)
④改变______________________________,重复上述测量和计算;再求出
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554509301.png)
①
(3分) ③
(3分) ④长木板的倾角(3分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025546341019.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025546491052.png)
试题分析:①设斜面倾角为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554681297.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554712932.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554727643.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554759866.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025547741117.png)
③木块做初速度为零的匀加速直线运动,
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002554993597.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002555008587.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002555039503.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025550551163.png)
④改变斜面的倾角进行多次实验,从而减小误差.
![](http://thumb2018.1010pic.com/images/loading.gif)
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