phy concept問題

這句 statement 是錯的，因為的確有些固體會遇熱收縮。所以改寫為

Most solid contracts when its temperature increases.

便正確了。

有關遇熱收縮的固體的資料，請參看
http://en.wikipedia.org/wiki/Negative_thermal_expansion

as we know, solid are made of particles which are tighly packed in crystal array.
and since every particles have their only kinetic energy, they would vibrate about their mean separation. as the temperature increases, generally, those particles would have more kinetic energy and they would vibrate with greater amplitude such that the mean separation between individual particles would be greater. therefore, this explains why solid expands on molecular level.

hope that it may help u understand.