档案法

Do you see the people standing on the sailing ship ? They give you a sense of how big the ship . What’s behind the ship? Is it a huge apartment complex? It’s just as massive as a very large building, but it’s not even resting on land. It’s a giant cruise ship, and it’s floating on water. The ship weighs about 100,000 metric tons. How can such a tremendous float on water? Why doesn’t it sink to the bottom of the ocean instead? Archimedes’ law explains why.
::你看见人们站在帆船上吗?他们给了你一条关于船有多大的感知。船后面是什么?船后面是一座巨大的公寓楼吗?它象一个很大的建筑一样庞大,但它甚至没有在陆地上休息。它是一艘巨大的游轮,漂浮在水面上。船的重量约为10万公吨。这样巨大的浮船怎么会在水面上?为什么它不沉到海底呢?Archimedes的法律解释了原因。

Archimedes Takes a Bath
::考古学需要洗澡

Did you ever notice when you get into a bathtub of water that the level of the water rises? More than 2000 years ago, a Greek mathematician named Archimedes noticed the same thing. He observed that both a body and the water in a tub can’t occupy the same space at the same time. As a result, some of the water is displaced, or moved out of the way. How much water is displaced? Archimedes determined that the volume of displaced water equals the volume of the submerged object. So more water is displaced by a bigger body than a smaller one.
::当你进入水浴缸时,你有没有注意到水位上升的情况?2000多年前,一位希腊数学家阿基米德斯(Archimedes)也注意到了同样的事情。他发现,水缸中的一具尸体和水不能同时占用同一空间。结果,有些水被移走,或者移动到另一边。有多少水被挪开?考古学确定,被移开的水量相当于被淹没的物体的体积。因此,更多的水被更大的体积而不是较小的体积所取代。

Q : If you jump into swimming pool, how much water does your body displace?
::问题:如果你跳进游泳池, 你的身体会流多少水?

A : The water displaced by your body is equal to your body’s volume. Depending on your size, this volume might be about 0.07 m ³ .
::甲:您身体中流出的水量相当于您身体的体积。视您体积大小而定,这个体积约为0.07立方米。

Displacement and Buoyant Force
::流离失所和生命力部队

Objects such as ships may float in a fluid like water because of buoyant force . This is an upward force that a fluid exerts on any object that is placed in it. Archimedes discovered that the buoyant force acting on an object equals the weight of the fluid displaced by the object. This is known as Archimedes’ law (or Archimedes’ principle).
::像船舶这样的物体可能漂浮在像水一样的液体中,因为浮力。这是一种向上力,一种液体对放置在其中的任何物体施加力力。 Archimedes发现,浮力在物体上的作用相当于被物体转移的液体的重量。 这被称为Archimedes的法律(或Archimedes的原则 ) 。

Floating Objects and Archimedes’ Law
::浮动物体和考古法

Archimedes’ law explains why some objects float in fluids even though they are very heavy. It all depends on how much fluid they displace. The cruise ship pictured in the opening image is extremely heavy, yet it stays afloat. If a steel ball with the same weight as the ship were placed in water, it would sink to the bottom. This is modeled in the Figure . The reason the ball sinks is that its shape is very compact, so it displaces relatively little water. The volume of water displaced by the steel ball weighs less than the ball itself, so the buoyant force is not as great as the force of gravity pulling down on the ball. Thus, the ball sinks.
::阿基米德斯的法律解释了为什么有些物体漂浮在液体中,尽管它们非常重。它都取决于它们流出多少液体。在开阔的图像中绘制的游轮是极其沉重的,但它却停留在浮点上。如果一个与船舶重量相同的钢球被放入水中,它就会沉到水底。这是以图为模型的模型。因为球汇的形状非常紧凑,因此它取代的水量相对较少。钢球流出的水量比球本身轻,因此浮力不会像重力拉下球一样大。因此,球汇就是如此。

Now look at the ship’s hull in the Figure . Its shape causes the ship to displace much more water than the ball. In fact, the weight of the displaced water is greater than the weight of the ship. As a result, the buoyant force is greater than the force of gravity acting on the ship, so the ship floats.
::现在看下图中的船体。其形状导致船流的水量比球多得多。 事实上,流水的重量大于船舶的重量。 因此,浮力大于船上的重力,因此,浮力会浮出水面。

Q : Why might you be more likely to float in water if you stretch out your body rather than curl up into a ball?
::问:为什么你更可能浮在水中 如果你伸展身体而不是弯曲成球?

A : You would displace more water by stretching out your body, so there would be more buoyant force acting on it. Therefore, you would be more likely to float in this position.
::甲:通过伸展身体,你将流出更多的水,这样就会有更多的浮力在水上活动。因此,你更有可能在这个位置漂浮。

Launch the PLIX Interactive below to apply Archimedes'  law to determine  if the crown is made of pure gold:
::启动下面的PLIX互动, 以应用Archimedes的法律来确定皇冠是否由纯金制成:

Summary
::摘要

播放段落
• Archimedes determined that an object displaces the same volume of fluid as its own volume.
  ::阿基米德确定,物体的流体量与其本身的体积置换液体量相同。
播放段落
• According to Archimedes’ law, the buoyant force acting on an object equals the weight of the fluid that the object displaces.
  ::根据Archimedes的法律,在物体上活动的浮力等于物体流体的重量。
播放段落
• The shape of an object may affect how much fluid it displaces and therefore the buoyant force acting on it. This explains why one object may sink while another object with the same weight but a different shape may float.
  ::对象的形状可能会影响它流出多少液体, 并因此影响它上浮的力。 这就解释了为什么一个物体会沉没, 而另一个物体则会沉没, 而另一个物体的重量相同, 但不同的形状可能漂浮 。

Review
::回顾

播放段落
1. What is Archimedes’ law?
   ::阿基米德的法律是什么?
播放段落
2. Fill in the missing word in the following sentence: An object will float in a fluid when the weight of the fluid displaced by the object is _______ than the weight of the object.
   ::填写以下句子中缺失的单词:当物体流出的液体重量为 + 大于物体重量时,物体将漂浮在液体中。
播放段落
3. Demonstrate how the shape of an object affects its ability to float using a container of water and two pieces of aluminum foil that are the same size and therefore the same weight. (Hint: Form the two pieces of foil into different shapes.)
   ::演示一个物体的形状如何影响它使用一个水容器和两块相同大小因而重量相同的铝泡沫来漂浮的能力。 (提示:将两块硫化物形成不同的形状。 )