一列简谐横波以1 m/s的速率沿绳子由A向B传播,质点A、B间的水平距离x=3

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问题:

一列简谐横波以1 m/s的速率沿绳子由A向B传播,质点A、B间的水平距离x=3 m,如图甲所示.若t=0时,质点A刚从平衡位置开始向上振动,其振动图如图乙所示.则B点的振动图象为右面四个图中的(  )

考点:简谐运动的概念
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Chinese proverbs are rich and they are still widely used in Chinese people’s daily life.   31  these proverbs there are often interesting stories. For example, the proverb, “plucking up a crop   32 (help) it grow”, is based on the following story.

It is said that a short—tempered man in the Song Dynasty (960—1279) was very anxious to help   33 rice crop grow up quickly. He was thinking about   34  day and night. But the crop was growing much slower than he expected.

One day, he came up with an idea   35  he would pluck up all of his crop a few inches. He did so the next day.

He was very tired   36  doing this for a whole day,   37  he felt very happy since the crop did “grow”  38 (high).

His son heard about this and went to see the crop. Unfortunately the leaves of the crop began to wither.

This proverb is saying we have to let things go in their   39 (nature) course. Being too anxious to help an event develop often   40 (result) in the contrary to our intention.

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海因里希最初提出的事故因果连锁过程包括如下五个因素遗传及社会环境;人的缺点;()

A.人的不安全行为或物的不安全状态

B.事故

C.破坏

D.伤害

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临床手术与麻醉的特点不包括()

A.损伤的必然性

B.技术的复杂性

C.病人的被动性及术前的焦虑心理

D.病人或家属的多项要求

E.过程中的风险性

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调节阀的尺寸选择不合格或特性不好,没有足够的()会使调节质量不高或不能调节。

A.严密程度

B.可调范围

C.负荷变动

D.线性度

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某生产线有2道工序,如下图所示,每道工序后有检验工序(用菱形表示),两道工序本身的初检合格率分别为90%和92%,A和B为返修工序,根据历史数据,进入返修的产品有50%能够修好,50%需要报废,假设检验能够检出所有不合格产品,以下说法正确的是()

A.整个生产线的直通率为91.2%

B.整个生产线的直通率为82.8%

C.整个生产线的直通率为87.4%

D.整个生产线的直通率为88%

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