I want you not to memorize every formula the book gives you for this problem.

我希望你们不要机械性地记忆,书上所给的这个问题的表达式

耶鲁公开课 - 基础物理课程节选

This is so obvious in this problem, but when you see more complicated formula, you may not know all the assumptions that went into the derivation and quite often you will be using it when you shouldn't.

在这道题中这些都很明显,但是当我们用更复杂的公式时,你可能搞不清楚所有,在推导时的前提,因此很多时候,你都会用错公式

耶鲁公开课 - 基础物理课程节选

So, that is a tricky problem to begin with because if you take this formula here, it tells you y if you know t, but no, we're not saying that.

以这个问题刚开始的时候有点难度,因为如果你要用这个公式,求y的时候就一定要知道t,但是,我们不知道

耶鲁公开课 - 基础物理课程节选