试题与答案

一人乘竖直电梯从1楼到12楼,在此过程中经历了先加速,后匀速,再减速的运动过程,

题型:多选题

题目:

一人乘竖直电梯从1楼到12楼,在此过程中经历了先加速,后匀速,再减速的运动过程,则下列说法正确的是(  )

A.电梯对人做功情况是:加速时做正功,匀速时不做功,减速时做负功

B.电梯对人做功情况是:加速和匀速时做正功,减速时做负功

C.电梯对人做的功等于人机械能的增加量

D.电梯对人做的功和重力对人做的功的代数和等于人动能的增加量

答案:

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参考答案:(1)合法原则。 (2)遵循资金使用的安全性、流动性和效益性原则。 (3)自愿、平等和诚实信用原则。 (4)公平竞争、密切协作的原则。

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