题干

如图所示为两个用摩擦传动的轮子,A为主动轮,已知A,B轮的半径比为R1:R2=1:2,C点离圆心的距离为
R
2
2
,轮子A和B通过摩擦的传动不打滑,则在两轮子做匀速圆周运动的过程中,以下关于两轮缘上A、B点及C点的线速度大小V、角速度大小ω、转速n之间关系的判断中正确的是(   )

A:VA=2VB

B:ωAC

C:ωA=2ωB

D:nB=2nA

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答案(点此获取答案解析)

C

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    Have you ever seen any students whose trousers hang so low you can see their underwear? What do you think of that? Fashionable? Some of today's teenagers are big fans of such a look.____.

    The headmaster of a school in central Italy has asked students to stop wearing low-rise jeans that expose underwear and part of the body. His request came after a class trip. One day, he saw one boy's baggy trousers slide to his feet ____.

    But in Italy, a nation that takes fashion very seriously, the suggestion caused a debate among parents, teachers and students. The issue is whether the headmaster's request will limit students' freedom—or whether dress in Italian schools is too casual.

    ____ “We do not want to kick fashion out.” the headmaster explained, “but extremes of fashion like this are not right in school.” Many other schools have now requested that their students also stop wearing such trousers.

    ____ Ludovica Gaudio, 14, wore extremely low trousers exposing orange underwear in class. It was cold, so she wore a matching orange scarf. ____ “I don't really feel comfortable in those sorts of jeans,” said Sarah Lattanzi, “in winter, when dressed like that, it's quite cold and I am afraid my stomach will ache.”

A. But recently this trend has been at the center of an argument in Italian middle schools.

B. A parents' group praised the move in favor of good taste, while others advised schools to stop worrying about fashion and fix up old school buildings.

C. He pointed out that this way of dressing is not suitable for school.

D. Most students have simply ignored the request.

E. Another 14-year-old said she would probably respect the request, simply for practical reasons.

F. Requests.

G. Schools should pay attention to things more important than students' clothes.