题目内容
如图所示,质量为m的飞行器在绕地球的圆轨道上运行,半径为
,要进入半径为
的更高的圆轨道Ⅱ,必须先加速进入一个椭圆轨Ⅲ,然后再进入圆轨道Ⅱ.已知飞行器在圆轨道Ⅱ上运动速度大小为v,在A点时通过发动机向后喷出一定质量气体使飞行器速度增加到
进入椭圆轨道Ⅲ,设喷出的气体的速度为u,求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156377262997.jpg)
(1)飞行器在轨道Ⅰ上的速度
及轨道Ⅰ处的重力加速度;
(2)飞行器喷出气体的质量;
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637664933.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637695940.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637711934.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156377262997.jpg)
(1)飞行器在轨道Ⅰ上的速度
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637742943.gif)
(2)飞行器喷出气体的质量;
(1)
=
·
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637789705.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637742318.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156377571057.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637773944.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637789705.gif)
(1)在轨道I上,飞行器所受万有引力提供向心力,设地球质量为M,则有:
G·
=m·![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156378201001.gif)
解得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156378201144.gif)
同理在轨道Ⅱ上![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156378351129.gif)
由①②可得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156378511204.gif)
在轨道I上重力加速度为
,则有G·
=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637898975.gif)
由③⑤可得
=
·![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637773944.gif)
(2)设喷出气体质量为Δm,由动量守恒得
=(m-Δm)
-Δm·u,
解得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156379761348.gif)
G·
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156378041042.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156378201001.gif)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156378201144.gif)
同理在轨道Ⅱ上
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156378351129.gif)
由①②可得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156378511204.gif)
在轨道I上重力加速度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637867944.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156378821042.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637898975.gif)
由③⑤可得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637742318.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156377571057.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637773944.gif)
(2)设喷出气体质量为Δm,由动量守恒得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637945977.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115637711934.gif)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156379761348.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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