题目内容
如图,一气缸水平固定在静止的小车上,一质量为m、面积为S的活塞将一定量的气体封闭在气缸内,平衡时活塞与气缸底相距L。现让小车以一较小的水平恒定加速度向右运动,稳定时发现活塞相对于气缸移动了距离d。已知大气压强为p0,不计气缸和活塞间的摩擦,且小车运动时,大气对活塞的压强仍可视为p0,整个过程中温度保持不变。求小车的加速度的大小。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082413504092813915.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082413504092813915.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041021999.png)
设小车加速度大小为a,稳定时气缸内气体的压强为
,活塞受到气缸内外气体的压力分别为
,![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041146596.png)
由牛顿第二定律得:
,
小车静止时,在平衡情况下,气缸内气体的压强应为
,
由波伊尔定律得:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041271606.png)
式中
,![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041349725.png)
联立解得:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041021999.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041053342.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041099558.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041146596.png)
由牛顿第二定律得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041193653.png)
小车静止时,在平衡情况下,气缸内气体的压强应为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041224372.png)
由波伊尔定律得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041271606.png)
式中
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041318500.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041349725.png)
联立解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135041021999.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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