Once you have started the boulder rolling, it develops momentum, which is defined by its mass and velocity.

一旦你开始让巨石滚动，巨石就会产生动量，这是由其质量和速度决定的。

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And in terms of equations that we use, it's sometimes easier to plug in the fact, since momentum is equal to mass times velocity.

在我们使用方程这方面，事实上有时是很容易代入的，因为动量等于质量乘以速度。

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Well, in physics, momentum is a vector, and it is a product between the mass of a particle and its velocity.

物理中，动量是矢量，它产生于,由粒子的质量与速度。

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And this is just a Newtonian expression of momentum, the product of the mass of the electron times its instant velocity.

这只是牛顿学上关于动量的表达，用电子质量,乘以瞬时速度。

麻省理工公开课 - 固态化学导论课程节选

We add momentum and velocity to the TV spot (the rain), capture it and circulate it back into the on-line process, thereby advancing the brand and buying cycle.

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The momentum of the Arab Spring is still gaining velocity, from Libya to Syria, but the U.S. and Israel are about to miss another historic opportunity.

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