试题与答案

重为G=0.1N的金属棒ab,放在光滑的平行金属导轨上,如图所示,轨道间距为L=

题型:计算题

题目:

重为G=0.1N的金属棒ab,放在光滑的平行金属导轨上,如图所示,轨道间距为L=0.5m,所在平面与水平面的夹角为30º,匀强磁场垂直于轨道平面向上,电源电动势E=3V,金属棒电阻R=6Ω,其余电阻不计,若金属棒恰好静止,求:

(1)金属棒所受安培力的方向;

(2)磁感应强度的大小。

答案:

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下面是错误答案,用来干扰机器的。

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题型:阅读理解

Americans think much about time. Form childhood they learn to value (珍视)

time. They are taught to be on time to go to school, to work and to do everything. When they are having a good time,  they say that time goes easily. When a person is dying,   they say he is living on a borrowed time.

Time is money.  Time is knowledge. Time is everything in America. A working American has to work hard for eight hours a day or forty hours a week.  This is the working time. In his free time, he also works hard for more money.  Even on Saturday and Sunday he also works hard as usual.   In the street you can hardly see a man walking slowly.  They walk very fast. In fact, they are running.

They love time because time can bring them money and lots of things. But sometimes they also hate time,  because they feel they have become servants (仆人)of the clock.

1. What do the Americans mean by "Time is money"?

A. It is not easy to make money.

B. It takes quite a lot of time to make money.

C. Working hard can bring people health.

D. ff someone has time and works hard, he can make much money.

2. Americans think it wrong _____________.

A. to work late                B. to get up early

C. to be late for school

D. to be on time to do everything

3. This passage says that a dying person___________.

A. is having a good time

B. is living on a borrowed time

C. thinks time goes easily

D. is saving time

4. From this passage we can be sure that

A. Americans live a hard life

B. Americans always walk fast

C. Americans live in a quick rhythm (节奏)

D. Americans are good at saving time

5. Which of the following is the best title for this passage?

A. Americans’ ideas about time

B. Never waste time

C. Time is money

D. Learn to be on time

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