This is how you get the rules for adding a vector to another vector, then taking a vector and multiplying it by some constant.

以上这些就是矢量加法的法则,以及数乘矢量的法则

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I want to consider a particle which has definite acceleration a, a constant one, but a is now a vector.

我想考虑一个加速度为 a 的质点,加速度恒定,但 a 是一个矢量

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take the derivative of this, get the velocity vector and you notice his magnitude is a constant Whichever way you do it, you can then rewrite this as v square over r.

对这个式子求一次导,就能得到速度矢量,你会发现其模长是常数,不管用什么方法,加速度也可以写成 v^2 / r

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