来自《耶鲁大学开放课程：生物医学工程探索 第18集 第18集》
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when forces are applied.材料才能发生物理移动 -
If this is a perfect elastic material like a rubber band如果它像橡皮筋或者物理课上讲过的弹簧 -
or like the springs you learned about in physics,是一种理想弹性材料 -
when I apply a force here,当我在这里施加一个作用力 -
it instantaneously changes its length.它的长度就会立即改变 -
Deformations are instantaneous; they take no time at all形变立即发生 对于理想弹性材料来说 -
for a perfect elastic material.发生形变不需要时间 -
How much would the deformation occur?形变量是多大呢 -
Well it would depend on the elasticity,这取决于弹性 -
but as soon as I added that force it's going to stretch out--但在我施加作用力的那一刻 它就伸长 -
bang--to that length and it's going to stay there.伸长到一定长度并保持 -
You know real materials don't behave like this你们知道真正的材料不会这样