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楼主 |
发表于 2-12-2009 07:07 PM
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把我害到最惨的就是PPS网络电视。它害我看动漫看到siao。 |
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发表于 2-12-2009 07:13 PM
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回复 220# ultikiller 的帖子
跟我一样分数~~~~很差哦！我的问题是不够了解~明明一句简单的东西却给我搞到很复杂将！ |
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楼主 |
发表于 2-12-2009 07:17 PM
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原帖由 -小麦- 于 2-12-2009 07:13 PM 发表 
跟我一样分数~~~~很差哦！我的问题是不够了解~明明一句简单的东西却给我搞到很复杂将！
你问的那三题的答案你还没给我。(+SI Unit) |
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发表于 2-12-2009 07:29 PM
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回复 223# ultikiller 的帖子
第三题答案？是什么问题了哦？！ 什么SI unit? |
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楼主 |
发表于 2-12-2009 07:34 PM
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楼主 |
发表于 2-12-2009 07:37 PM
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1）The diagram shows a boy appearing shorter when he is in a swimming pool.The depth of the water in the pool is 1.2m.
The refractive index of water is 1.33
What is the apparent depth of the pool?
2）The pressure of sea water at the bottom of an ocean is 1.3x10^8Nm^-2.What is the depth of the ocean?{density of sea water=1.02x10^3kgm^-3}
How 2 do?
3）The initial mass of radioactive element is 10g and its half life is 6 days.
Which of the following statements about the mass of the radioactive element is true?
anwer is A:6 days earlier,the mass is 20g
can somebody explain this answer to me?
我要答案+symbols。谢谢。 |
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发表于 2-12-2009 07:37 PM
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楼主 |
发表于 2-12-2009 07:39 PM
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原帖由 -小麦- 于 2-12-2009 07:37 PM 发表
将那题你会做了吗？答案是1.27x10^4咯！
我的答案是1.25x10^4。是不是错了? |
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楼主 |
发表于 2-12-2009 07:40 PM
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1）The diagram shows a boy appearing shorter when he is in a swimming pool.The depth of the water in the pool is 1.2m.
The refractive index of water is 1.33
What is the apparent depth of the pool?
2）The pressure of sea water at the bottom of an ocean is 1.3x10^8Nm^-2.What is the depth of the ocean?{density of sea water=1.02x10^3kgm^-3}
How 2 do?
3）The initial mass of radioactive element is 10g and its half life is 6 days.
Which of the following statements about the mass of the radioactive element is true?
anwer is A:6 days earlier,the mass is 20g
can somebody explain this answer to me?
我要答案+symbols。谢谢。 |
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发表于 2-12-2009 07:43 PM
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发表于 2-12-2009 07:48 PM
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回复 228# ultikiller 的帖子
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你算错了是吗？第1题每unit de ah!~~第三题我救在等着人家根我解释！ |
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楼主 |
发表于 2-12-2009 07:48 PM
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楼主 |
发表于 2-12-2009 07:49 PM
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原帖由 -小麦- 于 2-12-2009 07:48 PM 发表 
你算错了是吗？第1题每unit de ah!~~第三题我救在等着人家根我解释！
Physics 的？？？ |
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发表于 2-12-2009 07:51 PM
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DC的current比较大，
还是AC的current比较大？ |
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发表于 2-12-2009 07:51 PM
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回复 233# ultikiller 的帖子
你讲什么哦？ |
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楼主 |
发表于 2-12-2009 07:52 PM
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发表于 2-12-2009 07:53 PM
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发表于 2-12-2009 07:54 PM
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发表于 2-12-2009 07:55 PM
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原帖由 -小麦- 于 2-12-2009 07:53 PM 发表 
我猜是ac current。。哈哈！我不懂得啦！
我也是觉得是AC.... |
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发表于 2-12-2009 08:02 PM
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initial mass=10g
half life=6 days
这就代表说
这个radioactive substance
每6天，它的量就会减半
比如说，initial mass=a(只是个代表哈）
final mass=1/2(a)
3）The initial mass of radioactive element is 10g and its half life is 6 days.
Which of the following statements about the mass of the radioactive element is true?
anwer is A:6 days earlier,the mass is 20g
这个statement是对的
它说今天你看到那个东西是10g
6天之前它的mass还没有减半的时候是20g
所以今天它的mass是10g
再深入点看的话
6天之后它的mass再减半
就变成剩5g
12天之后再减半
就剩下2.5g
这样说会比较明白吗？
我怕会把你弄混淆了 |
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