Delta v is positive in this direction here, the work is negative. So work on the system is positive. Work done by the system is negative.

功是负的，总而言之,外界对系统做功的符号为正。

麻省理工公开课 - 热力学与动力学课程节选

So this plus plus is sort of shorthand notation for incrementation. So just add 1 to this variable's value, so now socks on feet is of course 1 and so next.

那么这个++符号是递增排序的,所以仅仅是对这个变量加一，现在袜子在脚上是一，那么下一个也是这样。

哈佛公开课 - 计算机科学课程节选

So, the system does work on the surroundings, hence the minus sign.

系统对环境做功，因此符号是负的。

麻省理工公开课 - 热力学与动力学课程节选

I don't want anybody to quit this class because they're worried about math or math notation.

我不希望你们因为对数学,或是数学符号的恐惧而放弃这门课

耶鲁公开课 - 博弈论课程节选

You add them all up algebraically, keeping track of their sign, and that's the total force.

你再对这些力做代数加法,注意符号,就求出合力了

耶鲁公开课 - 基础物理课程节选

I think an example might help those people who are disturbed by the notation.

让我来举一些例子来帮助那些,对这些符号感到困惑的同学

耶鲁公开课 - 博弈论课程节选

That great deal of specificity implies that heat is also path-dependent and again we have the convention that if heat is added to the system, the quantity is greater than zero.

热也是与路径有关的,根据通常的习惯,如果我们对系统加热，其符号取为正。

麻省理工公开课 - 热力学与动力学课程节选

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。

麻省理工公开课 - 热力学与动力学课程节选

I differentiate a second time and check the sign, so the second order condition, I differentiate this expression again with respect to q1.

我们对它进行二次求导然后看符号,这个式子的二阶导数,就是一阶导数再对q1进行求导

耶鲁公开课 - 博弈论课程节选

They're opposites for the pathway A.

对路径A，它们的符号是相反的。

麻省理工公开课 - 热力学与动力学课程节选