Again we have the charge of the nucleus on plus 2, +2 but let's say this time the electron now is going to be very, very close to the nucleus.

对于我们的氦原子，我们有一次得到了原子核电荷量为,但是我们说这次电子。

麻省理工公开课 - 化学原理课程节选

If you took the derivative of this, you will get the velocity at time t, it would be: v=v0+at.

如果你对它求导,你就可以知道 t 时刻的速度,即,v=v0+at

耶鲁公开课 - 基础物理课程节选

Consequently, for this object the position y, at any time t is known to be 15+10t-5t^.

因此,对这个物体来说,在任意时刻的位移y,就应该为15+10t-5t^

耶鲁公开课 - 基础物理课程节选

Then, to find the meaning of b, we take one derivative of this, dx/dt, that's velocity as a function of time, and if you took the derivative of this guy, you will find as at+b. That's the velocity of the object.

接下来,为了弄清b的含义,我们取它的一阶导数,dx/dt,得到速度作为时间的函数,如果你对它求导的话,你会得到at+b,这就是物体的速度

耶鲁公开课 - 基础物理课程节选