We know the pressure is equal to force per area.

我们知道压强等于力除以面积。

麻省理工公开课 - 热力学与动力学课程节选

The piston has a cross-sectional area, a, and the force pressure is force per volume area.

我们以活塞系统为例，来说明膨胀功。

麻省理工公开课 - 热力学与动力学课程节选

So in a town that's the size of new Haven with a population of let's say 100,000 people in just the immediate New Haven area, there might be 20 of these instances of very severe form of polio per year, 20 crippled children would result.

在一个像纽黑文这么大的城市里,大约有十万人口,生活在纽黑文地区的人当中,每年可能就会有二十人,感染到这种急性传染病,可能会导致二十个孩子残疾

耶鲁公开课 - 生物医学工程探索课程节选

Pressure is force per volume area.

气体就被压缩。

麻省理工公开课 - 热力学与动力学课程节选