So the signs in the velocity and the signs in average acceleration depend crucially on how I have defined my increasing value of x not where I choose my zero points.

所以速度的符号,和平均加速度的符号,这二者都取决于,这里x正方向,是如何定义的,和0点的选取没有关系。

youdao

So if you substitute that in there you get an average acceleration which is smaller than zero.

所以如果把它代进来，会得到一个，小于0的平均加速度。

youdao

The average acceleration 2 between time t1 and time t2 2 would then be the velocity at time t2 minus the velocity at time t1, divided by t2 minus t1.

在t1和t2之间的，这段平均加速度2，等于t2时刻的速度2，减去t 1时速度，再除以。

youdao

It's useful to have the average acceleration, which you can find by taking similar differences of velocities.

平均加速度也是很有用的,你可以用类似方法,取速度的变化量求出来

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