题目内容
某物理兴趣活动小组利用如右图装置可以验证机械能守恒定律,实验中电火花打点计时器所用交流电源的频率为50 Hz,得到如下图所示的纸带。选取纸带上打出的连续五个点A、B、C、D、E,现测出A点距起点O(初速度为零)的距离为x0=19.00cm,点A、C间的距离为x1=8.36 cm,点C、E间的距离为x2=9.88cm,取g= 9.8m/s2,测得重物的质量为100g。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500525622615176.jpg)
(1)选取O、C两点为初末位置研究机械能守恒。重物减少的重力势能是___________J,打下C点时重物的动能是___________J(保留三位有效数字);
(2)实验中,由于存在阻力作用,重物减少的重力势能总是大于重物增加的动能。依据实验数据来计算重物在下落过程中受到的平均阻力大小F=_________N(保留一位有效数字);
(3)根据纸带算出各点的速度v,测量出从O点开始下落的距离h,则以v2为纵坐标轴,以h为横坐标轴,画出的v2-h图像为图中的______。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250052562885187.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500525622615176.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256257518.png)
(2)实验中,由于存在阻力作用,重物减少的重力势能总是大于重物增加的动能。依据实验数据来计算重物在下落过程中受到的平均阻力大小F=_________N(保留一位有效数字);
(3)根据纸带算出各点的速度v,测量出从O点开始下落的距离h,则以v2为纵坐标轴,以h为横坐标轴,画出的v2-h图像为图中的______。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250052562885187.jpg)
(1)
,
(2)
(3)C
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256304810.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256335750.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256350616.png)
试题分析:(1)重力势能减小了:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250052563661409.png)
C点速度为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256382687.png)
动能增加量为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256413857.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256335750.png)
(2)根据功能关系有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250052564441193.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256350616.png)
(3)利用
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256491592.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256506796.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256522667.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005256538483.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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