如图所示,为空间直角坐标系,其中y轴正方向竖直向上。在整个空间中存在竖直向下的匀

题型:计算题

问题:

如图所示,为空间直角坐标系,其中y轴正方向竖直向上。在整个空间中存在竖直向下的匀强磁场,磁感应强度大小为B。现有一质量为、电荷量为q(q>0)的带电小球从坐标原点O以速度v0沿x轴正方向射出,重力加速度为g,空气阻力可忽略不计。

(1)若在整个空间加一匀强电场,小球从坐标原点O射出恰好做匀速圆周运动,求所加电场的场强大小以及小球做匀速圆周运动第一次通过z轴的坐标;

(2)若改变第(1)问中所加电场的大小和方向,小球从坐标原点O射出恰好沿x轴做匀速直线运动,求此时所加匀强电场的场强大小;

(3)若保持第(2)问所加的匀强电场不变而撤去原有的磁场,小球从坐标原点O以速度v0沿x轴正方向射出后,将通过A点,已知A点的x轴坐标数值为,求小球经过A点时电场力做功的功率。

考点:带电粒子在复合场中的运动
题型:计算题

阅读理解。

     If you ask people to name the one person who had the greatest effect on the English language, you will

get answers like "Shakespeare," "Samuel Johnson," and "Webster," but none of these men had any effect at

all compared to a man who didn't even speak English -William the Conqueror.

     Before 1066,in the land we now call Great Britain lived peoples belonging to two major language groups.

In the west-central region lived the Welsh, who spoke a Celtic language,and in the north lived the Scots,

whose language, though not the same as Welsh, was also Celtic.In the rest of the country lived the Saxons,

actually a mixture of Anglos, Saxons,and other Germanic and Nordic people,who spoke what we now call

Anglo-Saxon (or Old English ), a Germanic language. If this state of affairs had lasted, English today would

be close to German.

     But this state of affairs did not last. In 1066 the Normans led by William defeated the Saxons and began

their rule over England.For about a century,French became the official language of England while Old English

became the language of peasants. As a result,English words of politics and the law come from French rather

than German. In some cases,modern English even shows a distinction (区别) between upper-class French

and lower-class Anglo-Saxon in its words.We even have different words for some foods, meat in particular,

depending on whether it is still out in the fields or at home ready to be cooked,which shows the fact that the

Saxon peasants were doing the farming, while the upper-class Normans were doing most of the eating.

     When Americans visit Europe for the first time, they usually find Germany more "foreign" than France

because the German they see on signs and advertisements seems much more different from English than

French does.Few realize that the English language is actually Germanic in its beginning and that the French

influences are all the result of one man's ambition.

1. The two major languages spoken in what is now called Great Britain before 1066 were _____. 

A. Welsh and Scottish

B. Nordic and Germanic

C. Celtic and Old English

D. Anglo-Saxon and Germanic

2. Which of the following groups of words are,by inference,rooted in French?

A. president, lawyer, beef

B. president, bread, water

C. bread, field, sheep

D. folk, field, cow

3. Why does France appear less foreign than Germany to Americans on their first visit to Europe?

A. Most advertisements in France appear in English.

B. They know little of the history of the English language.

C. Many French words are similar to English ones.

D. They know French better than German.

4. What is the subject discussed in the text?

A. The history of Great Britain.

B. The similarity between English and French

C. The rule of England by William the Conqueror.

D. The French influences on the English language.

题型:计算题

()需求是受人尊重的需要。

A.生理

B.安全

C.社交

D.尊重

题型:计算题

英译汉:“cellulose”,正确的翻译为( )。

A.菌落
B.曲霉素
C.纤维素
D.氯霉素

题型:计算题

1978年6月2日,邓 * * 在()会议的讲话中着重阐述毛 * * 关于实事求是的观点,批评了在对待毛 * * 和毛 * * 思想问题上“两个凡是”的错误态度,并指出“一定要肃清林彪、‘ * * ’的流毒,拨乱反正,打破精神枷锁,使我们的思想来个大解放。

A.全军政治工作

B.中央组织工作

C.中央宣传工作

题型:计算题

50年代末前苏联有几大军种?分别是什么()

A、5,战略火箭军,国土防空军,空军,陆军,海军

B、4,战略火箭军,空军,海军,陆军

C、3,海军,陆军,空军

D、5,战略大箭军海军,陆军,空军,内卫部队

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