This formula doesn't tell you which way it's pointing, because it's a scaler; it's not a vector equation.

这个式子没有说明方向,因为这是一个标量而非矢量方程

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Vector equation A = B is actually a shorthand for two equations.

矢量方程 A = B 实际上是,两个方程的简写

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If you want to write it as a vector equation, you want to write it as v square over r minus-- I want to say that it's pointing in the direction toward the center.

如果要写出矢量方程,就应该写成 -v^2 / r,也就是说,方向就向圆心

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The advantage of introducing that guy is that if you like, I can now write an equation for the acceleration as a vector.

引入它的好处是,如果你愿意的话,我可以把加速度写成矢量形式

耶鲁公开课 - 基础物理课程节选