Now, gravity, well force, is equal to mass times acceleration, g and the acceleration due to gravity is g.
是重力,等于质量乘以加速度,由重力导致的加速度是。
Therefore, when you divide by the mass to get the acceleration, the response of different bodies is inverse to the mass.
因此,当你拿力除以质量得到加速度时,不同物体的加速度与质量成反比
You will learn in 8.02 that if you have a charged body changing direction, that constitutes an acceleration.
你们将在8。02中学到,如果一个带电体改变方向时,产生一个加速度。
So, a massless body cannot have a net force on it, because the acceleration of the rope cannot be infinite.
所以没有质量的物体不会受到力,因为绳子的加速度不可能是无穷大
Take the difference of the two velocities and divide by the difference of the two times, and you've got the acceleration.
求出速度的差值,除以时间的差值,这样就能得到加速度
In fact, it has to be some finite number, which is the acceleration of either of these two guys.
事实上它必须是有限的数值,也就是这两个物体某中某一个的加速度
Again, your common sense tells you, "Look, you are pulling something whose effective mass seems to be 5, the answer is 2."
你的常识会又一次告诉你,"你在拉一个相当于 5 千克的物体,所以加速度是 2 "
The answer is that simply knowing the particle has an acceleration is not enough to tell you where the particle will be.
答案是这样的,仅仅知道质点的加速度,是不足以告诉你它接下来的运动的
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
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
When you're falling to the surface of the Earth, you are describing a problem of constant acceleration.
当你讨论下落问题时,你在描述一个加速度恒定的问题
In other words, you don't have to be moving actually in a circle to have the acceleration.
也就是说,你不必真的在一个圆上运动以获得相应的加速度
If I pull the one kilogram mass and I let it go, it does something, some acceleration.
如果我拉 1 千克重的物体并松手,就会获得一个加速度
And know intuitively that if they move together, they will behave like an object of mass 5 and the acceleration will again be 2.
凭直觉认为既然它们一起运动,那么它们就相当于一个质量为 5 千克的物体,然后我们可以算出加速度为 2
And, you know acceleration means either change of speed or change of direction.
你知道加速度意味着,不是改变速度就是改变方向。
One is inertial mass, which is how much you hate your velocity to change, how hard you resist acceleration.
一个是惯性质量,它反映了物体速度改变的难易程度,即保持加速度的难易程度
But the acceleration it produces on the elephant and on the mass, are in an inverse ratio of their masses.
但这个力使大象和物体产生的加速度,与它们的质量成反比
You cannot have a spring pulled only at one side, because then it will then accelerate with infinite acceleration in that direction.
你不可能对弹簧只施加一边的拉力,因为那样的话弹簧就会以无穷大的加速度加速,就在这个方向上
Now I can measure that, because I pull it by one centimeter and I find the acceleration it exerts on a known mass.
现在就能测量这个力了,因为把弹簧拉伸 1 厘米,我就知道它让一个质量已知的物体产生的加速度
Simply knowing the acceleration is not enough to tell you where it was at the initial time.
仅仅知道加速度是,不足以告诉你它在初始时刻的位移的
So, when you divide by the mass to get the acceleration, you get the same answer.
因此,当等号两边除以质量来求加速度时,结果是相同的
This particle is constantly changing its direction, but it therefore has an acceleration and the acceleration, we have shown here, is pointing towards the center.
这个质点恒定地改变它的运动方向,因此它具有加速度,而且这个加速度,我们前面也讲过了,指向圆心
It says that, "If a body has an acceleration, then you need a force and the relation of the force to acceleration is this thing."
它是这么说的,"如果一个物体有加速度,那么你需要有一个力,力和加速度的关系是这样的"
A limited class of problems is one in which the acceleration is just a constant.
在这类有限的问题里,加速度均为常数
If every time I get the same acceleration, I'm convinced this is a reliable spring that is somehow producing the same force under the same condition.
如果每次都能得到相同的加速度,这个弹簧的可靠性就能令人信服,即它在相同的条件下能够产生相等的力
Their difference divided by the difference in times is going to be the acceleration.
它们的差值再除以时间的差值,就是加速度
That is 6 Newtons divided by 3 kg is also an acceleration of 2.
即,6 牛除以 3 千克同样得到加速度是 2
But if you imagine making these measurements more and more and more quickly, in the end, you can measure what you can say is the acceleration now.
但如果你想越来越短的时间内,测量这些数据,最终,你会测量出你所说的现在的加速度
As you start on the top and go down, your acceleration is negative.
当你在顶楼准备下降的时候,你的加速度是负的
Then you guys know, you just told me, acceleration is -9.8, We call it "minus" because it's accelerating down and up was taken to be the positive direction.
然后你们都知道,你告诉我,加速度是-9.8,我们取负号是因为加速度方向朝下,而正方向为竖直向上
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