设想用活塞向上提水,当活塞上提时,水略微有点膨胀,但在内聚力的作用下,水柱不会立即断开,但这时它施加在活塞上一个向下的力,而不是向上的压力,或者说,这时水的压强是负的,即负压强。当活塞提升到一定限度时,水柱断裂,与活塞分离。实验上测得,水负压的极限值可达300个大气压。
长期以来,木材皱缩现象一直被认为主要是因为木材中液体毛细张力产生的“负压强”压溃细胞壁造成的,该文对此提出了质疑。
The long-term existing theory of wood collapse which was thought to be caused by "negative pressure" resulted from capillary tension in the water capillaries was called in question.
负的压强没有意义?
这就是说,可以很简单的写出dG在,恒定压强下对温度的偏导数,是负。
That is, it's easy to write down straight away that dG with respect to temperature at constant pressure s is minus s.
应用推荐