问题 多选题

如图所示为两列沿同一弹性绳传播的简谐横波在某时刻的波形图,(虚线表示甲波,实线表示乙波),M为绳上x=0.2m处的质点,则下列说法中正确的是(  )

A.这两列波将发生干涉现象

B.图示时刻质点M的速度沿+y方向

C.由图示时刻开始,再经甲波周期的

1
4
,质点M的位移为20cm

D.因波的周期未知,故两列波波速的大小无法比较

答案

A、由图可知,两波的波长相等,又波速相等,则频率相等,能发生干涉.故A正确.

    B、两列波单独引起的M点振动方向沿+y方向,叠加后还沿+y方向.故B正确.

    C、再经甲波周期的

1
4
,质点M的位移为x=A1+A2>20cm.故C错误.

    D、沿同一弹性绳上传播的波速度相等.故D错误.

故选AB

阅读理解

Hobbs was an orphan(孤儿). He worked in a factory and every day he got a little money. Hard work made him thin and weak. He wanted to borrow a lot of money to learn to paint pictures, but he did not think he could pay off the debts.

One day a lawyer said to him, “One thousand dollars, and here is the money.” As Hobbs took the package of notes, he was very dumbfounded. He didn’t know where the money came from and how to spend it. He said to himself, “I could go to find a hotel and live like a rich man for a few days; or I give up my work in the factory and do what I’d like to do: painting pictures. I could do that for a few weeks, but what would I do after that? I should have lost my place in the factory and have no money to live on. If it were a little less money, I would buy a new coat, or a radio, or give a dinner to my friends. If it were more, I could give up the work and pay for painting pictures. But it’s too much for one and too little for the other.”

“Here is the reading of your uncle’s will(遗嘱),” said the lawyer, “telling what is to be done with this money after his death. I must ask you to remember one point. Your uncle has said you must bring me a paper showing exactly what you did with his money, as soon as you have spent it.”

“Yes, I see. I’ll do that,” said the young man.

小题1:Hobbs wanted to borrow money to _____.

A.study abroad

B.work abroad

C.pay off the debts

D.learn to paint pictures小题2:What does the underlined word “dumbfounded”(in Paragraph 2) probably mean?

A.Surprised.

B.Frightened.

C.Satisfied.

D.Excited.小题3:With the money he got, at first Hobbs _____.

A.planned to have a happy life for a few days

B.decided to give up his work in the factory

C.was to give a dinner to his friends

D.had no idea what to do小题4:Hobbs was asked to _____.

A.tell the lawyer what he did with the money after spending it

B.read his uncle’s will

C.tell the lawyer what was to be done with the money

D.buy some pictures

单项选择题