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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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Let's plot droplet velocity as a function of looking at the number that have this velocity 0 with the zero being in the center here.
我们将液滴的速度设定为,观察那些数字作用，在中心的地方,速度为。
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The second piece of information we need to know is what actually the kinetic energy is of the ejected electron, and that's something we can just measure by measuring its velocity.
其次，我们需要知道的信息是,出射电子的动能，这可以通过,测量它们的速度得到。
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Then, to find the meaning of b, we take one derivative of this, dx/dt, that's velocity as a function of time, and if you took the derivative of this guy, you will find as at+b. That's the velocity of the object.
接下来,为了弄清b的含义,我们取它的一阶导数,dx/dt,得到速度作为时间的函数,如果你对它求导的话,你会得到at+b,这就是物体的速度
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There are no other molecules on that side of the wall. So there's an attractive force that makes the velocity within not quite as fast.
墙的另一边没有分子,因此吸引力,会降低球的速度。
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What de Broglie is saying we can know the wavelength of any matter at all, as long as we know its mass and it's velocity.
通过德布罗意所说的,只要我们知道了,它的质量和速度，我们可以知道,任何物质的波长。
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When you're driving in your car, there's a needle and the needle says 60; that's your velocity at this instant.
当你在开车时,有一根指针指着60,表示你这个时刻的速度
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So, if we kind of think about the numbers we would need, we would actually need a velocity that approached something that's about 10 to the negative 30 meters per second.
所以如果我们稍微想想，我们需要的数值是多少，我们需要一个,大约为10的负30次方米每秒的速度。
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This is the starting speed, that's the rate at which it is gaining velocity, and that's how long it's been gaining it.
这是起始时的速度,这是速度的增长速率,这是加速的时间
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It's very interesting because velocity seems to require two different times to define it -- the initial time and the final time.
这非常有趣,因为速度似乎需要两个时间才能算出来,初时刻和末时刻
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NO So that the more complete answer to the question is that no, we're never going to be able to observe that because of the uncertainty principle it's not possible to observe a velocity that's this slow for a macroscopic object.
所以这个问题的完整答案是，由于不确定性原理,我们不可能测量到这么慢的,宏观物体的速度，希望这个解释。
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There's infinite number of them, but they're all moving relative to each other at constant velocity.
有无数个惯性观察者,但是他们都在相对于彼此,做匀速运动
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It's in the nature of things to go at a constant velocity.
能保持恒定速度是物体的固有性质
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Let's talk about velocity just for completeness.
为了完整起见，我们接下来要讲速度。
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We divide that by the mass, so 0.12 kilograms, that's the mass of a regulation baseball for the major leagues, and the velocity of the baseball is 42 meters per second. So, we can cross out our units doing our unit analysis.
我们用质量来除它，质量为0，12千克，这是大多数联赛规定的棒球质量,棒球的速度为42米每秒,所以，我们可以消去单位,来做单位分析。
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That's another way of saying maintaining velocity if it's not acted upon by a force.
这就是不受外力作用时,速度保持不变的另一种说法
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Just take the derivatives and that's the velocity vector.
直接计算对时间的导数就是速度矢量
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x = 0 plus-- What's the horizontal velocity?
= 0 加上,水平方向的速度是多少
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So it's useful to have the average velocity.
平均速度还是很有用的
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That's the point where velocity is 0.
也就是速度为零的点
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It's a different constant velocity.
只不过是速度不同而已
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Frequencies, how many times you go around, f is revolutions per second It's called the angle of velocity.
频率就是一秒转多少圈,因为 f 是每秒转过的圈数,这就是角速度
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If you want to know how fast it's moving at a given time, if you want to know the velocity, I just take the derivative of this answer, which is 10-10t.
如果你想知道它在给定时刻的运动有多快,如果你想知道它的速度,我只要对这个式子求导,得到10-10t
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