"Buildings in Jakarta are built to withstand horizontal acceleration of about and this earthquake which just happened yesterday maybe about five percent of gravity,"
VOA: standard.2009.09.07
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
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
Gates' stressed that,in any case, he saw no cause for a slowdown in the pace of U.S.troop pullouts, but that any acceleration, would necessarily depend on an assessment of the situation by U.S.Commander Ray Odierno.
VOA: standard.2009.07.29
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。
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
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
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
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
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
The acceleration gives you an extra stuff, quadratic in time.
加速度对位移有额外贡献,是时间的二次项
Acceleration is measured in meters per second squared.
加速度的单位是米每秒平方
When a particle moves in a circle, it has an acceleration towards the center of this size, v^2 over R.
当一个质点在圆周上运动时,它有一个指向圆心的加速度,v^2 / R
It tells you when a particle moves in a circle, it has an acceleration in a negative R direction, namely directed towards the center.
它告诉你当一个物体在圆周上运动时,它有一个在 -R 方向的加速度,也就是说是直接指向圆心的
We said, "Let's take, for the simplest case that we can possibly imagine, namely a particle moving in one dimension along the x-axis with a constant acceleration a.
我们说过,"考虑我们可以想象的最简单的情况,即质点在一维空间运动,沿着 x 轴且保持恒定加速度 a
Whenever you see a particle moving in a circle, even if it's at a constant speed, it has an acceleration, v square over r directed towards the center.
只要看到质点做圆周运动,即使是匀速圆周运动,也存在一个加速度,大小为 v^2 / r,方向指向圆心
If it's going in a circle, you will say from now on, that it, indeed, has an acceleration, even though no one's stepping on the accelerator, of amount v^2 over R.
如果它在一个圆周上运动,你会说从现在起它其实有加速度,即使没有人去踩油门,加速度大小为 v^2 / R
You can see that if a was equal to g, your downward acceleration is that of gravity, namely the cable has snapped in the elevator, Then you don't feel any weight.
你会发现如果 a 等于 g,你下降的加速度就是重力加速度,也就是电梯的绳索断了,那时你会完全失重
Then, in every situation where the body has an acceleration a, the location has to have this form, where this number is where it was initially, this was the initial velocity of the object.
在任何研究对象具有加速度a的情况下,它的位移就一定具有这种形式,这个系数代表了它的初位移,这个代表了它的初速度
The most important result from last time was that if you took this r, and you took two derivatives of this to find the acceleration, d^2 r over dt^2, try to do this in your head.
上节课最重要的结论,就是如果你把 r 写成这样,对 r 求两次导就能得到加速度,d^2 r / dt^2,心算一下
So, we know in this example the initial height should be 15 meters and the initial velocity should be 10, and for acceleration, I'm going to use -g and to keep life simple, I'm going to call it -10.
我们知道在这个例子中,初始高度为15米,初始速度为10,然后是加速度,我们用"-g"表示重力加速度,为了计算方便,加速度的值取为-10
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