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问题 问答题

小丽在学习了热学知识后，她想估算一下自己家每天烧水做饭需要的热量，于是仔细记录了她家每天烧水、煮饭、炒菜的时间，并把它折算成烧水时间，相当于每天将30Kg 20℃的水烧开（在1标准大气压下）

（1）小丽家每天烧水做饭需要多少热量？

（2）如普通煤的热值为3×107 J/Kg，从理论上讲小丽家每天烧水做饭需要多少千克的煤？

（3）小丽家实际每天的用煤量是2Kg，由此她算出她家炉子的效率是16.8%，她家煤炉效率低的原因是什么？

（4）从大的方面来看，家里煤炉除了效率低，浪费能源外，另一个主要缺点是什么？

答案

已知：水的质量m=30kg，初温t0=20℃，末温t=100℃，水的比热c=4.2×103J/（kg•℃），普通煤的热值为q=3×107J/kg

求：（1）水吸收的热量Q吸=？；（2）燃烧煤的质量m′=？

（1）水吸收的热量：

Q吸=cm（t-t0）=4.2×103J/（kg•℃）×30kg×（100℃-20℃）=1.008×107J；

（2）燃烧煤放出的热量等于水吸收的热量，Q放=Q吸=1.008×107J，

∵Q=mq，

∴燃烧煤的质量：

m′=

Q放
q
=
1.008×107J
3×107J/kg
=0.336kg；

（3）煤炉效率低的原因：煤燃烧不充分；热量散失严重等；

（4）家用煤炉的缺点：不安全，煤气中毒；引起火灾；大气污染；不卫生等．

答：（1）小丽家每天烧水做饭需要1.008×107J热量；（2）小丽家每天烧水做饭需要0.336kg 的煤；（3）家煤炉效率低的原因是煤燃烧不充分；热量散失严重等；（4）家里煤炉的另一个主要缺点是不安全，煤气中毒；引起火灾；大气污染；不卫生等．

单项选择题

PQRST法，属于记忆技巧法的一种，其中R是指（）。

A.预习或浏览要记住的段落内容

B.向自己提问该段的目的或意义

C.仔细阅读材料

D.用自己的话陈述从段落中得到的信息

E.用回答问题的方法检验自己的记忆
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问答题

Mr. Vice Premier, the Finance Minister,
Mr. Mayor, Ladies and Gentlemen,
Let me, first of all, return the compliment, on behalf of all of us, to you, Mr. Vice Premier, to you, Mr.Minister, and you, Mr. Mayor, for the great contribution that you have made to the success of this meeting. Idon’t think any of us could have imagined a more well-organized conference or a more warm welcome thanyou have given us here in Shanghai, and I would like everyone to join me in expressing our thanks to you.[TONE]∥[TONE]
I would like to make just two general comments.
The first is that all of us have to work politically to ensure that poverty and the alleviation of poverty arecentral on the global agenda. I believe that today it is not central on the global agenda. I believe that todaylip service is given to the question of poverty. The real issues today that seem to be on the mind of theworld—terrorism, Iraq, Afghanistan, the budget deficits—are the visible problems that must be dealt with,that are immediate, while attention is given less to the equally inevitable and the equally dangerous problemsthat come with poverty. [TONE]∥[TONE]
We must deal with the question of social equity and social justice. Because without dealing with thatquestion of poverty, there can’t be any peace, and $900 billion being spent on military expenditure, $300billion being spent on agricultural subsidies, and $50- or $60 billion being spent on overseas developmentassistance is one of the absurdities that we have to change. [TONE]∥[TONE]
And the second and last thing I’d like to say is that we have talked about economics, we have talkedabout advances that must be made for social justice, and we’ve talked about steps that need to be taken inempowerment and in the methodologies that we can use to scale up. [TONE]∥[TONE]
But the one thing that we have not talked about and that I think all of us need to recognize is that if weare to be effective in advocating the case for poverty reduction, and hopefully eradication, is that we have to do it with a sense of belief that what we are doing is right. We should be addressing the question of poverty not just from economics, but because dealing with equity and social justice is right. [TONE]∥[TONE]
We should not be afraid to say that there is a human content in what we’re doing, but there is alsoa moral and, if you like, spiritual content in what we’re doing. We are not here just as economists. Weare here because we owe every human being in the world an opportunity and a chance to fulfill theirdestiny. [TONE]∥[TONE]
And so going out from this meeting I hope we feel a little bit uplifted and a little bit responsible to goout from here to deal with the question of scaling up of poverty alleviation because it’s right, and as membersof the human race, it’s something that we should do.
Thank you very much to our hosts, and thank you all for being here. [TONE]∥[TONE]
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