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问题 问答题

一物体在某一行星表面上做自由落体运动，在连续的两个1s内，下降的高度分别为12m和20m，若该星球的半径为100km，则环绕该行星的卫星的最小周期为多少？

答案

根据物体做匀变速直线运动则有△x=at2        ①

由于在连续的两个1s内，下降的高度分别为12m和20m，

由此得该行星表面的重力加速度g′=

△x
t2
=
20-12
1×1
m/s2=8m/s2  ②

由万有引力定律及牛顿运动定律得

  

GmM
R2
=mg′得出：g′=
GM
R2
       ③

   

GmM
R2
=m
4π2R
T2
得出：T=2π
R3
GM
   ④

由③得：GM=g′R2，代入④得：

T=2π

R
g′

代入数值得T=702.1 s  

答：环绕该行星的卫星的最小周期为702.1 s．

解答题

小数16.85读作十六点八五，请按这个方法读出下列小数．

14.55读作：______；

4.50读作：______；

2.07读作：______；

101.1读作：______．
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单项选择题

A variety of illegal acts committed by people in the course of their employment, for their own personal gain, are collectively known as white-collar crime. Embezzlement, theft and trading securities (1) insider information are common forms of white-collar crime. The majority of cases involve low-level employees who steal because they are under (2) financial stress. Many plan to (3) the money back as soon as possible but may never do so. Their crimes are usually never (4) because the amounts of money are small, and no one notices the (5) .

(6) , there are some very large cases of white-collar crime, such as multimillion-dollar stock market or banking seams that take years to discover and are extremely difficult and expensive to (7) .

White-collar crime is not (8) to the business sector. Government employment, especially (9) the city level, also provides opportunities to (10) one’s pockets. (11) , building inspectors accept bribes and full-time employees receive (12) payments.

Although white-collar crime is less (13) than street crime, it involves (14) more money and harm to the public than crimes committed by street criminals. It is (15) that there are more criminals (16) the office suites than in the streets, yet the (17) of white-collar makes it difficult to uncover the offenses and pursue the offenders. As the economy (18) from manufacturing to services and electronic commerce, opportunities for white-collar crime (19) , while the technology needed to stop such crimes will (20) .

7（）

A.pursue

B.persecute

C.proceed

D.prosecute
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