The characters 膨胀 péng zhàng is a rather interesting lot. Together, this set means expand or inflate. 膨 means swollen, bloated or inflated. 胀 means swollen, inflate or expand. They actually have similar meanings.

当物体受热时,其中的粒子的运动速度就会加快,因此占据了额外的空间,这种现象称为 膨胀.固体、液体、气体都有膨胀现象,液体的膨胀率约比固体大10倍,气体的膨胀率约 比液体大100倍左右。膨胀有好有坏,比如,温度计的使用就是利用液体膨胀的原理。 而铁轨之间的缝隙则是为了使铁轨不被膨胀所破坏。

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Examples of usage include:

  • 金属收了热就会膨胀了 When metals absorb heat, they will expand.
  • 消费膨胀 Inflated consumption.
  • 膨胀性 Expandability. (Remember anything with a 性 at the end means a degree of change. See my 性 list here.)