加速度和速度都是矢量。
我可以测量它了，因为我把它拉到了一厘米，我发现它对一个已知质量施加的加速度。
I can measure that, because I pull it by one centimeter and I find the acceleration it exerts on a known mass.
不要把沿圆周的切向加速度与向心加速度混淆。
Do not confuse ever the tangential acceleration, which is along the circumference, with centripetal acceleration.
在同一时期内，X 射线光源亮度的增加速度要快得多。
The increase in brightness of the x-ray sources over the same period has occurred far faster.
意识到了这种程度的恶性通货膨胀和面值的增加速度没法维持下去，匈牙利平格就被新货币福林所取代。
Realizing that this type of hyperinflation and denomination increase was not sustainable, the Pengo was replaced by the Forint.
仅为重力加速度的,五分之一。
随着它的旋转，就产生了加速度。
角加速度等于，角速度的导数。
And angular acceleration is the derivative of angular velocity.
就加速度而言这意味着什么呢？
这节课主要讨论速度和加速度。
这样我们，就能求出向心加速度。
And we can calculate now what the centripetal acceleration is.
如果加速度减小，振荡周期变大。
If the acceleration goes down, the period of oscillation goes up.
这意味着加速度与位矢平行。
So, that means the acceleration is parallel to the position.
大致是重力加速度的40倍。
它还是得碎,因为加速度,实在太大了。
Something breaks because the magnitude of acceleration becomes too high.
我们称之为“向心加速度
目前为止，是关于速率，平均速度和加速度。
All right, so far, about speeds and average velocities and accelerations.
这也就是瞬时加速度。
我们还学过加速度，也就是速度向量的导数。
And, we've also learned about acceleration, which is the derivative of velocity.
若弹力巨大，那么在物体上的，加速度就大。
If I have a huge spring force, the acceleration on a given mass will be high.
一个很小的加速度。
如果存在一个力矩，就会产生一个，角加速度。
And if there is a torque, there's going to be an angular acceleration.
我们在上节课讲了推力和拉力，可产生加速度。
Last time we discussed that an acceleration is caused by a push or by a pull.
现在我将和你们一起，计算圆柱会获得的加速度。
Now I would like to calculate with you the acceleration that a cylinder would obtain.
小球受到绳子的拉力，这就是向心加速度的来源。
This ball is feeling a pull from the string and that provides it with the centripetal acceleration.
下面这张图描述了一些发射过程的竖直加速度分布。
Here is a plot of the distributions of the vertical accelerations for a variety of bird shots.
若存在净转矩，就会产生角加速度，正如你们所见。
If there is a net torque, there will be an angular acceleration, and that's what you see.
乘客可接受的加速度和基于整车性能预期的制动策略。
Acceptable occupant accelerations and restraint strategies based on expected vehicle performance.
速度的符号已经，由负变正了，可是加速度又还是正的。
It has changed from a minus sign to a plus sign because of this positive acceleration.
速度的符号已经，由负变正了，可是加速度又还是正的。
It has changed from a minus sign to a plus sign because of this positive acceleration.
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