题目内容
水滴由屋檐落下,它通过下方一高为1.4m的窗户用时0.2s,求屋檐距窗户下沿的高度。(空气阻力不计,g=10m/s
)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746165243.png)
H=3.2m
本题考查自由落体的运动规律及公式
设屋檐距窗户下沿的高度为
,水滴由屋檐落下到窗户下沿的时间为
,则有
①;
设屋檐距窗户上沿的高度为
,水滴由屋檐落下到窗户上沿的时间为
则有
②;
由①②得
即![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746337475.png)
所以![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746493440.png)
故![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241237465081144.png)
所以屋檐距窗户下沿的高度为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746774517.png)
设屋檐距窗户下沿的高度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746181399.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746212300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746228566.png)
设屋檐距窗户上沿的高度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746259494.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746290441.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746321849.png)
由①②得
即
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746337475.png)
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746493440.png)
故
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241237465081144.png)
所以屋檐距窗户下沿的高度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123746774517.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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