9.1 动议
Section outline
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The wings of this hummingbird are moving so fast that they're just a blur of motion. You can probably think of many other examples of things in motion. If you can't, just look around you. It's likely that you'll see something moving, and if nothing else, your eyes will be moving. So you know from experience what motion is. No doubt it seems like a fairly simple concept. However, when you read this article, you'll find out that it's not quite as simple as it seems.
::这只蜂鸟的翅膀移动得太快, 以至于它们只是运动的模糊点。 你可能会想到其他许多在动的例子。 如果你不能, 环顾四周。 你可能会看到一些在动的东西, 如果没有其它东西, 你的眼睛会动起来。 所以你从经验中知道什么是运动。 毫无疑问,它看起来像一个相当简单的概念。 但是, 当你读了这篇文章, 你会发现它并不那么简单。Defining Motion
::界定动议In science , motion is defined as a change in position. An object's position is its location. Besides the wings of the hummingbird in the opening image, you can see other examples of motion in the Figure . In each case, the position of something is changing.
::在科学中,运动的定义是位置的改变。物体的位置是它的位置。除了开张图像中蜂鸟的翅膀外,你可以在图中看到其他运动的例子。在每种情况下,某物的位置都在变化。Q : In each picture in the Figure , what is moving and how is its position changing?
::问题:在图中的每一幅图中,什么在移动,其位置如何变化?A : The train and all its passengers are speeding straight down a track to the next station. The man and his bike are racing along a curving highway. The geese are flying over their wetland environment. The meteor is shooting through the atmosphere toward Earth, burning up as it goes.
::A:火车及其所有乘客正从一条轨道上直奔下一站。 这个人和他的自行车正在沿着弯曲的高速公路赛车。 鹅正在飞越他们的湿地环境。 陨石正在向地球发射, 随风燃烧。Launch the simulation below to observe two moving robots, Irwin and Ruthie, as they race to the elevator and learn more about motion:
::开始下面的模拟 观察两个移动的机器人,Irwin和Ruthie, 当他们奔向电梯 了解更多运动:Frame of Reference
::参考框架参考框架There's more to motion than objects simply changing position. You'll see why when you consider the following example. Assume that the school bus pictured in the Figure passes by you as you stand on the sidewalk. It's obvious to you that the bus is moving, but what about to the children inside the bus? The bus isn't moving relative to them, and if they look at the other children sitting on the bus, they won't appear to be moving either. If the ride is really smooth, the children may only be able to tell that the bus is moving by looking out the window and seeing you and the trees whizzing by.
::比物体更需要运动,只是改变位置。你会看到为什么当你考虑下面的例子。 假设图中显示的校车在你站在人行道上时通过。 很明显, 校车正在移动, 但对于公共汽车里的孩子来说, 车没有相对移动, 如果他们看着坐在公共汽车上的其他孩子, 他们也不会看起来在移动。 如果车程很顺畅, 孩子们只能通过看着窗外看车, 看见你和树的呼唤才能知道公车在移动。This example shows that how we perceive motion depends on our frame of reference . Frame of reference refers to something that is not moving with respect to an observer that can be used to detect motion. For the children on the bus, if they use other children riding the bus as their frame of reference, they do not appear to be moving. But if they use objects outside the bus as their frame of reference, they can tell they are moving.
::这个例子表明,我们如何看待运动取决于我们的参照框架。 参照框架指的是对于可以用来探测运动的观察者来说没有移动的东西。 对于公共汽车上的儿童来说,如果他们利用乘坐公共汽车的其他儿童作为参照框架,他们似乎没有移动。 但是,如果他们使用公共汽车外的物体作为参照框架,他们可以知道他们正在移动。Q : What is your frame of reference if you are standing on the sidewalk and see the bus go by? How can you tell that the bus is moving?
::问:如果你站在人行道上看到公交车经过,那你的参照基准是什么?你怎么知道公交车在动?A : Your frame of reference might be the trees and other stationary objects across the street. As the bus goes by, it momentarily blocks your view of these objects, and this helps you detect the bus' motion.
::A: 您的参照框架可能是街对面的树和其他固定物体。 当公交车经过时, 它瞬间堵住了您对这些物体的视线, 这帮助您检测到公交车运动 。Watch this video to observe an involving the motion of a tennis ball:
::观看这段影片以观察网球运动:Summary
::摘要-
Motion is defined as a change of position.
::动议的定义是立场的改变。 -
How we perceive motion depends on our frame of reference. Frame of reference refers to something that is not moving with respect to an observer that can be used to detect motion.
::我们如何看待运动取决于我们的参照框架。参照框架指的是对于可以用来探测运动的观察员来说没有变化的东西。
Review
::回顾-
How is motion defined in science?
::科学如何定义运动? -
Describe an original example that shows how frame of reference influences the perception of motion.
::描述一个说明参照框架如何影响运动感知的原始例子。
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Motion is defined as a change of position.