生活中常出现这种情况:鞋带明明系得很紧,但没过多久就松了。而如今科学家认为他们找到了这个问题的答案。美国加州大学伯克利分校的机械工程师们利用慢动作摄像机开展了一系列实验,发现在各种力的复杂相互作用下,鞋带系成的绳结只需几秒便可松开。实验开始时,研究生克里斯汀·格雷格先穿上一双跑鞋,系紧鞋带,然后在跑步机上慢跑,一名同事则负责拍下这一过程。结果发现,脚在慢跑时砸中 This is often the case in life: the laces are obviously very tight, but not too long to loose. Now scientists think they have found the answer to this question. Mechanical engineers at the University of California, Berkeley, used a series of experiments with slow-motion video cameras to find that the knotted lace could be released in seconds with the complex interaction of forces. At the beginning of the experiment, graduate student Christine Greg first put on a pair of running shoes, fasten the shoelace, and then jogging on a treadmill, a colleague is responsible for the filming of the process. The results showed that the foot hit the jogging