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问题 选择题

关于简谐运动，下列说法正确的是（   ）

A．简谐运动方程X=Asin(ωt+φ)中，A表示振幅，ω表示圆频率，φ表示相位

B．简谐运动中势能增加的过程是靠 * * 衡位置的过程

C．单摆简谐运动中，回复力是由合外力的切向分量提供的

D．半径很大的光滑圆弧面上有一小球，把它从最低点移开一小段距离后放手，小球将做简谐运动

答案

CD

简谐运动方程中，φ表示初相位，A错误；简谐运动中势能增加的过程是离开平衡位置的过程，B错误；根据简谐振动的特点可判断出CD正确。

填空题
一根绳子长
2
5
米，截成等长的5段，每段是全长的______．
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单项选择题

Modern industrial society grants little status to old people. In fact, such a society has a system of built-in obsolescence. There is no formal system for continuing our education throughout our life in order to keep up with rapidly changing knowledge. When our education and job skills have grown obsolete, we are treated exactly like those who have never gained an education or job skills and are not encouraged or given the opportunity to begin anew.As a society becomes more highly developed, the overall status of older people diminishes. Improved health technology creates a large pool of old people, who compete for jobs with the young. However, economic technology lowers the demand for workers and creates new jobs for which the skills of the aged are obsolete, forcing older people into retirement. At the same time, young people are being educated in the new technology and are keeping pace with rapid changes in knowledge. Finally, urbanization creates age-segregated neighborhoods. Because the old live on fixed incomes, they must often live in inferior housing. All these factors — retirement, obsolete knowledge and skills, inferior standards of living — lower the status of the aged in society.A century ago, when one could expect to live only to 50 or so, the life span more or less coincided with the occupation and family cycle. But today the average life span allows for fifteen to twenty years of life after these cycles. It appears that our life span is outpacing our usefulness in society.

The more highly developed a society is,________.

A．the more advanced technology will be

B．the larger the number of people will be

C．the more diminished old people’s status will be

D．the lower the overall status of the people will be
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