问题 多选题

甲、乙两单摆在同一地点做简谐运动的图象如图,由图可知(  )

A.甲和乙的摆长一定相等

B.甲的摆球质量较小

C.甲的摆角大于乙的摆角

D.摆到平衡位置时,甲和乙摆线所受的拉力可能相等

答案

A、C、由图可知,甲和乙两摆的周期相同;则由单摆的周期公式可知,T=2π

L
g
可知,两摆的摆长一定相同;故A正确;

B、因为单摆的周期与摆球质量无关,故B错误;

C、摆长相同,而甲的振幅大,故甲摆的摆角大,故C正确;

D、在最低点时,拉力与重力的合力充当向心力,则有:F-mg=m

v2
r
;解得F=m(g+
v2
r
);因为摆长相等,但偏角不同,故到达底部时的速度不同;同时因为质量不同;故拉力有可能相同;故D正确;

故选:ACD.

阅读理解

第二部分阅读理解(共25小题。第一节每小题2分,第二节每小题1分;满分45分)

第一节 阅读下列短文,从媒体所给的四个选项(A,B,C,D)中,选出最佳选项,并在答题卡上将该项涂黑。(共20小题;每小题2分,满分40分)

A

A beggar followed a lady and asked her for some money. She refused, so he turned away sadly and said he must do what he had made up his mind to do.

At this word, the lady was greatly frightened for she was afraid for his life. So she called him back and gave him a dollar. The beggar took the money, put it into his pocket, and thanked her a great deal. “You have saved me from a terrible fate,” he said. The lady asked him what he meant. The beggar replied, “Madame, I have been begging all day, but only you have taken pity on me. Without this dollar you gave to me, I should have had to go to work now.

41. Before meeting the lady, the beggar ________.

A. had already received some dollars already

B. had been thinking of taking his own life

C. had received no money for that day

D. had acted as if he was looking for a job

42. If the woman had understood the beggar’s words correctly, she would probably _____.

A. have given him one more dollar

B. have persuaded him to give up begging

C. have gone away without giving him any money

D. have offered him some work

43. In the story, “a terrible fate” means _______

A. to beg     B. to go to work    C. to die   D. to live a hard life

44. The best headline(标题) for the story is ______.

A. How to Beg              B. Money before Everything    

C. Anything except Work     D. Work for Money

单项选择题