it won't be going quite as fast.

它不会再运动得那么快
And we also know,

我们也知道
when it overshoots the other side, it will not go back to - A;

当它冲到另一边时它不会达到 - A
normally, it will go back to - A.

正常情况下它会到达 - A
Everyone knows why it goes back to - A, right?

大家都知道为什么它能达到 - A 对吧
When you go the other extremity without friction,

那你在没有摩擦的情况下运动到另一端
your energy is all potential.

能量全为势能
It was (1/2) · k · A^2 to begin with,

初态时是 (1/2) · k · A^2
it's going to be (1/2) · k · A^2 at the end,

末态时还是 (1/2) · k · A^2
except A can become - A without changing the answer;

只是 A 可能变成 - A 但答案不变
that's why it'll go from A to - A.

这就是为什么它能从 A 走到 - A
But when you've got friction,

但当有摩擦时