问题 选择题

(2011•柳州一模)已知地球质量是月球质量的81倍,地球半径是月球半径的3.8倍.已知某一近地卫星绕地球运动的周期为1.4小时,由此估算在月球上发射“近月卫星”的环绕周期约为(只考虑月球对卫星的引力)(  )

A.1.0小时

B.1.6小时

C.2.1小时

D.3.0小时

答案

卫星绕地球和月球做匀速圆周运动时,根据万有引力提供向心力,

   G

Mm
R2
=m
4π2R
T2

得,T=2π

R3
GM
,其中R为星球半径,M为星球质量.

则得到:“近月卫星”的环绕周期与近地卫星的周期为  T:T=

R3月
R3地
M
M

代入解得,T=1.6h

故选B

多项选择题
单项选择题

The United States is usually given credit for creating and developing the musical comedy as it is known today. The first musical shows were based (1) everyday American life and the (2) development of the form took place in the United States for more than half a century. (3) the early 1970s, (4) , the London theater has (5) the Broadway stage.

The Black Crook, which opened at Niblo’s Garden in New York City on Sept. 12, 1866, is usually (6) as the inspiration for musical comedy. A troupe of French ballet dancers (7) to be stranded in New York without work (8) a fire damaged the theater (9) they had been booked. In order to keep a (10) to them, the theater producer put the dancers into a melodrama written by Charles M. Barres.

The first stage production that was (11) a musical comedy was a show that was (12) from the Prince of Wales Theater to the Gaiety Theater in London in 1892. Staged by George Edwards, the show called In Town featured a chorus line of Gaiety Girls. The (13) year A Gaiety Girl was equally successful, and a (14) of the show played in New York in the same year. When it was (15) in newspapers, it was designated a musical comedy and regarded as a new (16) of entertainment.

It did not take the form long to (17) in the United States. Almost (18) one of the most renowned talents of the American stage went to work on his own musicals. The singer-dancer George M. Cohan staged Little Johnny Jones in 1904. Cohan, (19) own life story was made into the musical George M (1968), also wrote the books, words, and (20) for Forty-five Minutes from Broadway ( 1906 ), The Little Millionaire ( 1911 ), The Song and Dance Man ( 1923 ), and American Born (1925).

8()

A.because

B.thus

C.but

D.hence