【英语时差8,16】硬币可以叠多高？（上）

Here’s a question of burning scientific importance. How high can you stack¹ pennies before they fall over? The answer? It depends. In a perfect universe, with perfectly² flat pennies that align³ exactly on top of each other, the stack could go as high as you wish. In the real universe, however, you’ll be lucky if you can get them above about one foot. Why Do They Always Fall Over? It’s because of the center of gravity. The center of gravity is the point where all the individual weights average out. The entire stack acts as if its weight were located only at the center of gravity! Now, since the center of gravity is the average of all those pennies’ weights, it will always be in the middle of the stack. That means the higher you make the stack, the higher the center of gravity goes.

1 stack   

n.堆叠，堆；vt.堆积，成叠放在；vi.堆成一堆

参考例句：

• There's a whole stack of bills waiting to be paid.有一大堆账要付呢。
• They are specially packaged so that they stack easily.它们经过特别包装以便于堆放。

2 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。

3 align   

vt.使成一线，结盟，调节；vi.成一线，结盟

参考例句：

• Align the ruler and the middle of the paper.使尺子与纸张的中部成一条直线。
• There are signs that the prime minister is aligning himself with the liberals.有迹象表明首相正在与自由党人结盟。