时差N小时 为什么冰不滑

Try telling someone who has just fallen on a patch of ice that ice is not slippery and they'll think you're crazy. But, in fact, ice itself isn't slippery because it is a solid. One quality of solids is that when two solids are together there is friction¹ between them that will keep them from slipping.

告诉某个刚在冰上滑倒的人冰其实不滑，那人肯定会觉得你疯了。不过事实的确如此，冰本身并不滑，因为它是固体。固体的一个特点就是当两个固体接触时会产生摩擦防止打滑。

So how can your shoe slip on ice? The answer lies in two peculiar² properties of ice. The first is that as water freezes, its molecules³ move farther apart. The molecules of most substances move closer together as they freeze, making them shrink at lower temperatures.

因此，为什么你的鞋子会在冰上打滑？原因在于冰具有两种特性。第一种特性就是水结冰时，水分子分离得更远。但多数物质在结冰时，分子会紧密聚集在一起，温度一降低物质就会收缩。

But water molecules move farther apart at temperatures below 39 degrees Fahrenheit⁴, making water expand as it freezes. That is why frozen water pipes burst, and a tray of ice cubes will freeze over its top if you fill it too full. The second peculiar property of ice is directly linked to its first peculiarity⁵.

但当温度低于39摄氏度时，水分子会分散开来，因此结冰后冰的体积大于水的体积。这就是为什么水管会冻裂，用盘子盛满水，结冰后冰面会超过容器的平面。冰的第二种特性与第一种特性是直接相关的。

When subjected to pressure, ice melts. Remember that the molecules in ice are farther apart than the molecules in water; therefore ice molecules are vulnerable to pressure which pushes them closer together, causing the ice to change into water.

冰在压力作用下会融化。记住冰的分子比在水的状态时更分散，受压后导致分子聚集，此时冰会变成水。

So when you step on a patch of ice, you exert pressure on the ice, which causes its molecules to move closer together. That makes them revert⁶ to their more dense⁷ state, which is water. If you slip on a patch of ice, then, you in fact are slipping on a thin layer of water that the pressure from your weight has created. And, unlike solid ice, water, as a liquid , is quite slippery.

所以，当你踏在一块冰上时，会对它产生压力，这个压力导致分子相互间靠得更近，使之恢复到更加紧密的形态——水。如果你在冰面上打滑了，实际上是你在一层薄薄的水面上打滑了，而这些水正是因为你体重带来的压力导致的。跟固态的冰不一样，液态的水是相当滑的。

1 friction   

n.摩擦，摩擦力

参考例句：

• When Joan returned to work,the friction between them increased.琼回来工作后，他们之间的摩擦加剧了。
• Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体，并使其停止。

2 peculiar   

adj.古怪的，异常的；特殊的，特有的

参考例句：

• He walks in a peculiar fashion.他走路的样子很奇特。
• He looked at me with a very peculiar expression.他用一种很奇怪的表情看着我。

3 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

4 Fahrenheit   

n./adj.华氏温度；华氏温度计(的)

参考例句：

• He was asked for the boiling point of water in Fahrenheit.他被问到水的沸点是华氏多少度。
• The thermometer reads 80 degrees Fahrenheit.寒暑表指出华氏80度。

5 peculiarity   

n.独特性，特色；特殊的东西；怪癖

参考例句：

• Each country has its own peculiarity.每个国家都有自己的独特之处。
• The peculiarity of this shop is its day and nigth service.这家商店的特点是昼夜服务。

6 revert   

v.恢复，复归，回到

参考例句：

• Let us revert to the earlier part of the chapter.让我们回到本章的前面部分。
• Shall we revert to the matter we talked about yesterday?我们接着昨天谈过的问题谈，好吗？

7 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。