Be careful, and this is going to be especially complicated and confusing when we get to quantities that have a more obscure meaning like entropy.
大家要小心,如果需要测量的物理量,如熵,没有很明确的意义,那么着可能变得很复杂。
So, that can be a little bit confusing for us to think about, and when it's a very good question you might, in fact, say well, maybe there's not zero probability here, maybe it's just this teeny, teeny, tiny number, and in fact, sometimes an electron can get through, it's just very low probability so that's why we never really see it.
这想起来有点令人困惑,你们可能会说也许,这里的概率并不是严格的为零,而是非常非常小,所以有时电子就可以穿过去,这是个,很好的想法。
Convention, OK, this negative sign is just a pure convention. You just got to use it all the time. If you use an old textbook, written when I was taking thermodynamics, they have the opposite convention, and it's very confusing. But now we've all agreed on this convention, and work is going to be with the negative sign here.
系统对外界做功的符号为负,这就是我们,在本课中的规定,纯粹出于统一符号的需要,有些教科书中,可能会使用相反的符号规定,注意不要混淆了,这门课上,我们将一直使用。
And the nucleus name was used as an analogy to the nucleus of a cell so in some ways that makes it easier to see the connection but I think it can also be a little bit confusing for maybe 7th graders that are learning both at the same time, that this nucleus acts very different from a nucleus in a cell, although, of course, there many of them in the nucleus of a cell.
原子核这个名字的命名,是类似于细胞核,这样会让人们更容易看到两者之间的联系,但我觉得这样可能,会给正在学这两个课程的,7年级学生带来困惑,原子核的行为,和细胞核完全不同,虽然在细胞核。
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