题目内容
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241153195285583.jpg)
如图所示为气体实验装置,开始时玻璃管内封闭的空气柱长度为3 cm,此时气压表显示容器内气体的压强
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319543561.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319559246.gif)
(1)这一过程中气体分子的平均动能如何变化?
(2)最终气压表的示数是多少?
(3)若在另一次快速压缩气体过程中,气体内能增加1.5 J,气体放出的热量为1.4J,那么活塞对气体做功是多少?
(1)平均动能不变(2)
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319575423.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319559544.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319575423.gif)
(1)缓慢压缩,气体温度不变。所以气体分子的平均动能不变-----2分
(2)L0 =" 3" cm ,L =" 2" cm ,![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319543561.gif)
设压缩后气体压强为
,由玻意耳定律:
---------------2分
解得:
----------------1分
(3)由热力学第一定律:
--------------2分
解得:
-------------------------------1分
(2)L0 =" 3" cm ,L =" 2" cm ,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319543561.gif)
设压缩后气体压强为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319933202.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319949510.gif)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319559544.gif)
(3)由热力学第一定律:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115320136490.gif)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115319575423.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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