1.为什么玻璃杯遇忽冷忽热时会裂开?玻璃是热的不良导体,且易碎。当玻璃杯内外的温差较大时,内外的膨胀就不一致。例如,在冷杯内注入热开水,则杯内的圆周就要增大,但杯外的玻璃温度仍未升到和杯内相同,故杯外圆周还未来得及增大,于是就被杯内的玻璃挤裂了。 1. Why does the glass break when it is hot and cold? The glass is a poor conductor of heat and is brittle. When the temperature difference between the inside and the outside of the glass is large, the expansion inside and outside is not uniform. For example, injecting hot boiled water into a cold cup increases the circumference of the cup, but the temperature of the glass outside the cup does not rise to the same value as the inside of the cup. Therefore, the outer circumference of the cup also has an increase in the future, so it is in the cup. The glass was cracked.