题目内容
长度L=0.4m的细线,拴着一个质量m=0.3kg的小球,在竖直平面内作圆周运动,小球运动到最低点时离地面高度h=0.8m,此时细线受到的拉力F=7N,g取10m/s2,求:
(1)小球在最低点速度的大小;
(2)若小球运动到最低点时细线恰好断裂,则小球着地时速度为多大?
(1)小球在最低点速度的大小;
(2)若小球运动到最低点时细线恰好断裂,则小球着地时速度为多大?
(1)最低点有
,
m/s;
(2)根据机械能守恒,
,解得:
m/s。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133252154785.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133252185579.png)
(2)根据机械能守恒,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133252217985.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133252263611.png)
(1)最低点有
,
m/s;
(2)根据机械能守恒,
,解得:
m/s。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133252154785.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133252185579.png)
(2)根据机械能守恒,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133252217985.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133252263611.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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