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“和平号”空间站已于2001年3月23日成功地坠落在南太平洋海域，经过与大气摩擦，空间站的绝大部分经过升温、熔化，最后汽化而销毁，剩下的残片坠人大海．此过程中，空间站原来的机械能E中，除一部分能量Q用于销毁和一部分能量被残片带走外，还有一部分能量通过其他方式散失（不考虑坠落过程中化学反应的能量）．已知质量为m的残片以声速v坠海，从开始坠落至入海时残片的温度升高了△T（每千克空间站材料温度升高1K平均所需能量为c）．则通过其他方式散失的能量Eˊ=______．

答案

根据题意，空间站的机械能E

在坠落过程中，用于销毁所需的能量为Q

用于残片升温所需的能量为Q残=cm△T

残片入海时的动能为E残=

1
2
mv2

以E'表示其他方式散失的能量，则由能量守恒得E=Q汽+E残+Q残+E'

        E′=E-Q-E残-Q残

各式整理E′=E-Q-

1
2
mv2-cm△T

答案：E-Q-

1
2
mv2-cm△T

单项选择题 案例分析题

女性，51岁，孕3产3， * * 不规则流血3个月，量时多时少。既往月经规律，3～4天/28～30天，放置宫内节育器（惰性不锈钢环）20年。

临床上首选的治疗方法是()

A.高效大剂量孕激素治疗

B.孕激素后半期疗法

C.子宫内膜切除术

D.子宫+双附件切除术

E.子宫+右侧附件切除术

F.雌孕激素序贯治疗

G.雌孕激素联合治疗
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Tragedies have a way of making people rethink their (1) and find a new focus. They make people think about what a society needs in order to (2) . The notion of doing something to take control of society or of our fate as humans might be dated back to ancient times of the (3) . Now, in the early 21st century, " social (4) " are trying to take back some (5) over society’s direction once again. A social inventor is not necessarily a social (6) , a social (7) or someone who works in a (8) industry or invents new (9) and consumer products. A social inventor is using the power of (10) thinking, to come up with ideas for (11) in certain communities or sections of society. They have a vision of a (12) world and create new systems or practices. Their ideas may seem (13) or impossible. They are usually quite (14) people. But some of these creative thinkers have (15) and quietly changed the way we live. Social inventions do not have to be (16) . Sometimes they are new (17) for neighborhoods or communities, or even very (18) ideas. The idea of social inventions has become so popular in recent years. It shows how much people desire to make a (19) in our society and not remain (20) .
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