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单选题 39.花样滑冰运动员绕通过自身的竖直轴转动,开始时两臂伸开,转动惯量为
,角速度为
;然后将两手臂合拢,使其转动惯量为
,则转动角速度变为( )
A. 
B. 
C. 
D. 
学科：默认课程
时间：2026-05-04 21:39:42
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题目1单选题
How many days will the woman rent the carA. TwoB. ThreeC. FourD. Five
题目2单选题
Why does the woman decide to rent a ToyotaA. Because it is a new modelB. Because its rental rate is lowerC. Because its colour is more attractiveD. Because it is more comfortable
题目3单选题
What can we learn about the woman from the conversationA. She enjoys making new friendsB. She likes doing volunteer workC. She gets along well with her colleaguesD. She possesses the qualities of a good leader
题目4单选题
What kind of job is the woman going to takeA. Meeting people in personB. Talking with people over the phoneC. Introducing products to customersD. Making schedules for the manager
题目5单选题
How many hours will the woman work a weekA. ThreeB. SixC. NineD. Twelve
题目6单选题
23.几个力同时作用在一个具有固定转轴的刚体上,如果这几个力的矢量和为零,则此刚体( )A. 必然不会转动B. 转速必然不变C. 转速必然改变D. 转速可能不变,也可能改变
题目7单选题
39.花样滑冰运动员绕通过自身的竖直轴转动,开始时两臂伸开,转动惯量为<img src="https://tihai-oss-cloud.itihey.com/img/ccde104b472356a04c44710e568fbe75.jpg">,角速度为<img src="https://tihai-oss-cloud.itihey.com/img/fe36643615ea36f97d1d5ed0c55757e5.jpg"> ;然后将两手臂合拢,使其转动惯量为<img src="https://tihai-oss-cloud.itihey.com/img/9937eb556aadd4b020c5e4a289f8fc6d.jpg"> ,则转动角速度变为( )A. <img src="https://tihai-oss-cloud.itihey.com/img/69ffef5950344c56e99a6385da3b0755.jpg">B. <img src="https://tihai-oss-cloud.itihey.com/img/828b8a99ecd6b9cf24de5c93aad38438.jpg">C. <img src="https://tihai-oss-cloud.itihey.com/img/7e1530066afb092dc22d07dc5d25073f.jpg">D. <img src="https://tihai-oss-cloud.itihey.com/img/058a3d82b6397a9f4c316cd363aa2e56.jpg">
题目8单选题
33.一人站在有光滑固定转轴的转动平台上,双臂水平地举二哑铃.在该人把此二哑铃水平收缩到胸前的过程中,人、哑铃与转动平台组成的系统的( )A. 机械能守恒,角动量守恒B. 机械能守恒,角动量不守恒C. 机械能不守恒,角动量守恒D. 机械能不守恒,角动量也不守恒
题目9判断题
平行于转轴的力对转轴的力矩一定等于零,而垂直于转轴的力对转轴的力矩一定不为零A. 正确B. 错误
题目10判断题
作用在定轴转动刚体上的合力矩为零,刚体转动的角加速度为零A. 正确B. 错误
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