阅读下列有关明清时期徽商的材料，回答问题。

材料一新都(新安)，勤俭甲天下，故富亦甲天下。贾人娶妇数月，则出外或数十年，至有父子邂逅而不相识者。大贾辄数十万，则有副手而助耳目者数人。其人皆铢亮不私，故能以身得幸于大贾无疑，他日计子母息，大羡，副者始分身自为贾。

——顾炎武《肇域志·徽州府》

材料二徽郡商业，盐、茶、木、质铺(典当业)四者为大宗。茶叶六县皆产，木则婺源(地名)为盛，店铺几遍郡国，而盐商成萃于淮、浙。

——陈去病《五石脂》

材料三江南各地的徽杭大贾，不仅贩布，而且染布、踹布(将布踹压平整使其紧薄有光)；不仅贸丝，而且开车缫丝。

——翦伯赞主编《中国史纲要》

材料四大抵徽俗，人十三(十分之三)在邑，十七在天下；其所积蓄，则十一在内，十九在外。

——王世贞《四部稿》

如图所示，小型工件P以速率v₁在光滑水平工作台上滑行，水平传送带AB段的长为L，以速度v₂运行，工件P从A处滑上传送带，与传送带间的动摩擦因数为μ，在达到B点之前已经与传送带保持相对静止，请就工件速率v₁和传送带的速度v₂的大小关系提出假设，并得出相应的工件P在传送带上由A运动到B所有的时间．

    Robert and Henry were going home from school, when, on turning a corner, Robert1out, "A fight! Let us go and see!" "No," said Henry; "Let us go quietly home and avoid this quarrel. We have2to do with it, and may get into trouble."

    "You are not a brave boy, and afraid to go, "said Robert, and off he ran. Henry went straight home, and in the afternoon went to school, as usual,3 Robert had told all the boys that Henry was a coward, and they laughed at him a great deal.

    A few days4, Robert was bathing with some schoolmates and 5his depth. He struggled and screamed for help, but all in vain. The boys 6 had called Henry a coward, got away from the water as fast as they could, but they did not even try to help him. Robert was fast 7, when Henry threw off his clothes, and sprang into the water. By great effort, and8much danger to himself, he brought Robert to the shore, and thus saved his life.

    Robert and his schoolmates were9at having called Henry a coward. They admitted that he had more10than any of them.

    Never be afraid to do good, but always fear to do evil.