能量的种类

Lesson Objectives
::经验教训目标

• Describe ways in which energy can be transferred.
  ::说明可以转让能源的方式。

• Describe kinetic energy.
  ::描述动能

• Identify types of potential energy.
  ::查明潜在能源的类型。

• Give examples of energy conversions.
  ::举例说明能源转换。

Lesson Vocabulary
::词汇表课程

• energy transfer
  ::能源转让转让

• potential energy 
  ::潜在能能能

• kinetic energy
  ::动动能能量

Introduction
::导言

Did you ever babysit younger children? If you did, then you probably noticed that young children are very active. They seem to be in constant motion. It may even be hard to keep up with them. Where does the ability to move quickly come from? Another way to say this is that kids have a lot of energy. But what is energy? 
::你有没有照顾过更年幼的孩子?如果你照顾过孩子?如果你照顾过,那么你可能就会注意到,幼儿非常活跃。他们似乎在不断运动。甚至可能很难跟上他们。行动的能力从哪来?另一种说法是,孩子的精力很大。但是,什么是能量?

 

Defining Energy
::界定能源

Energy is the ability to do work. Another way to say this is, the ability to cause change. Work is done when a force is used to move something. When work is done, energy is transferred. This transfer occurs between one object and another. For example, a batter swings a bat and transfers energy. She transfers her energy to the bat. The moving bat, in turn, transfers energy to the ball. Energy is measured in the joule (J).
::能源是工作的能力。 另一种说法是, 促成变化的能力。 当使用一种力量来移动某个东西时, 工作就完成了。 当工作完成时, 能量就会转移。 这种转移发生在一个对象和另一个对象之间。 例如, 击球会挥动蝙蝠, 转移能量。 她会将能量转移到蝙蝠身上。 移动蝙蝠反过来又将能量转移到球上。 能量在焦耳( J) 中测量 。

 

Energy exists in many forms. One form of energy is called mechanical. Mechanical energy is the energy of motion. This type of energy can also include things that are not yet in motion. In these cases, they have only a potential to be in motion. In most cases, this ability comes from a position. A rock sitting on top of a cliff has potential energy. It is more than just the ability. A rock sitting on the ground could move if someone picked it up. This is not the type of potential we are referring to here. A boulder sitting on a cliff may get pushed loose. The natural force of gravity  will  pull it down because it cannot stay hanging in mid-air. This is far different to saying a rock may move because of a random event. Therefore, it has the potential to be in motion. 
::一种能源形式以多种形式存在。 一种能源形式叫做机械。 机械能源是运动的能量。 这种能源形式也可以包括尚未动动的东西。 在这些情况下, 它们只有运动的潜力。 在大多数情况下, 这种能力来自一个位置。 悬崖顶上的岩石有潜在的能量。 这不仅仅是能力。 如果有人把它捡起来, 地面上的岩石可以移动。 这不是我们这里所指的潜力类型。 悬崖上的石头可能会被推散。 自然引力会拉下它, 因为它不能停留在空中。 这与说岩石可能随机移动完全不同。 因此, 它具有运动的潜力。

Another way to store energy is by changing an object's shape. If you stretch a rubber band, it is storing energy. When the rubber band is released, the rubber band moves.  
::另一种存储能量的方法是改变物体的形状。 如果您拉伸一个橡胶带, 它就是储存能量。 当橡胶带被释放时, 橡胶带就会移动 。

Kinetic Energy
::动能能

What do all the photos in   below have in common? All of them show things that are moving. Kinetic energy is the energy of motion. Anything that is moving has kinetic energy. This applies to atoms as well as planets. Things with kinetic energy can do work. Therefore, they can cause change. For example, the hammer in the photo is doing the work. It is pounding the nail into the board. In other words, the hammer is causing a change by moving the nail.
::下面所有照片的共同点是什么? 它们都显示着移动的东西。 动能是运动的能量。 动能是运动的能量。 任何移动都有动能。 这适用于原子和行星。 有动能的东西可以发挥作用。 因此, 它们可以带来变化。 例如, 照片中的锤子正在起作用。 它正在把钉子敲到板上。 换句话说, 锤子正在通过移动钉子来改变。

 

The amount of kinetic energy in a moving object depends on its mass and velocity. An object with greater mass or greater velocity has more kinetic energy.
::移动物体的动能量取决于其质量和速度。质量或速度较大的物体具有更多的动能。

Potential Energy
::潜在能源

Did you ever see a scene like the one in   below? In many parts of the world, trees lose their leaves in autumn. The leaves turn color. Then fall from the trees to the ground. As the leaves are falling, they have kinetic energy. While they are still attached to the trees they also have energy. When they are attached they are not in motion, so how can they have energy? Instead of kinetic energy, they have stored energy. This stored energy is called potential energy.
::你曾没有看见像下面那样的景象吗?在世界许多地区,树叶在秋天都枯萎,树叶变色,然后从树上掉到地上。树叶落下的时候,树上有动能。叶子落下的时候,树上有动能。当树上没有动能的时候,树上没有动能,怎么没有动能呢?它们却储存了能量。这种贮存的能量被称为潜在能量。

An object has potential energy because of its position. For example, leaves on trees have potential energy because they could fall. They fall because of the pull of gravity. Potential energy can be transferred into motion. Motion can also be turned back into potential energy. Objects have potential energy due to their position. A leaf on a tree branch has potential energy. The leaf's energy can be turned into motion as it falls. Once the leaf is on the ground, it has no more potential unless it is lifted back up. What pulls these falling leaves to the ground? How does it provide potential energy for objects? 
::一种物体由于其位置而具有潜在的能量。 例如, 树上的叶子有潜在的能量, 因为它们可能坠落。 它们会坠落。 它们会因为引力而坠落。 潜在的能量也可以被转移到运动中。 运动也可以被恢复为潜在的能量。 物体由于其位置而具有潜在的能量。 树枝上的叶子有潜在的能量。 树枝上的叶子有潜在的能量。 叶子一旦坠落, 就会变成运动。 一旦叶子在地面上, 它就没有更大的潜力, 除非它被抬起来。 是什么把叶子拉到地面上? 它如何为物体提供潜在的能量?

 

Gravitational Potential Energy
::重力潜能能源

Gravitational Potential Energy is affected by position. Like the leaves on trees, anything that is raised up has the potential to fall. It has potential energy. You can see examples of people with gravitational potential energy in   below.
::引力潜能能源受到位置的影响。像树上的叶子一样,任何升起的东西都有可能坠落。它有潜在的能量。您可以看到下面有引力潜能的人的例子。

 

Gravitational potential energy depends on two things. It depends on its weight, because a large falling rock can do more damage than a leaf falling from a tree. It also depends on its height above the ground. Like the skateboarder, the higher the ramp, the faster he will be going when he reaches the bottom. Like all energy, gravitational potential energy has the ability to do work. In this case, weight has the potential to deliver a force. More important for us is that it has the ability to cause change. What kind of change you may ask? Gravitational potential energy has the ability to cause motion. 
::引力潜在能量取决于两件事。 它取决于它的重量, 因为一个巨大的坠落岩石比从一棵树上掉下来的叶子能造成更大的破坏。 它也取决于它的高度。 和滑板机一样, 坡道越高, 当他到达底部时, 他的速度越快。 和所有能量一样, 引力潜在能量都有能力发挥作用。 在这种情况下, 重量具有释放力量的潜力。 对我们来说, 更重要的是它有能力带来变化。 您可以要求什么样的变化? 引力潜在能量有能力引起运动 。

Elastic Potential Energy
::弹性潜能能源

Another type of energy is related to its shape. This energy is called elastic potential energy. This energy results when some objects are stretched or squeezed. For something to be elastic, it must have the ability to return to its same shape. For example, the rubber band in   below has been stretched. Will it spring back to its original shape when released? Some springs can be elastic when they are squeezed. Other springs are elastic when they are stretched. What will happen when the handspring is released? 
::另一种类型的能量与它的形状有关。 这种能量被称为弹性潜在能量。 当某些物体被拉长或挤压时, 这种能量产生效果。 要使某些物体具有弹性, 它必须有能力恢复到相同的形状。 例如, 下面的橡胶带已经拉长了。 当释放时, 它会回到原来的形状吗? 当它们被挤压时, 有些泉水会具有弹性; 当它们被拉长时, 其它泉水会具有弹性。 当手跳出来时会发生什么?

 

Energy Conversion 
::能源转换

What happens when a diver jumps off the diving board? His gravitational potential energy changes to kinetic energy as he falls. In other words, he falls faster and faster until reaching the water. However, he can always regain his potential energy. All he must do is get out of the water and climb back up. This requires an input of kinetic energy. These changes in energy are examples of energy conversion. Energy can be converted from one form to another. It can also be transferred from one object to another. 
::当潜水员跳下潜水板时会发生什么情况?当潜水员跳下潜水板时,他的重力潜在能量在下降时会改变动能。换句话说,他下降得更快,直到到达水面。然而,他总是可以重新获得潜在的能量。他要做的就是从水中跳出来,再爬上去。这需要动力能量的输入。这些能量的变化是能源转换的例子。能源可以从一种形式转换为另一种形式。它也可以从一种形式转移到另一种形式。它也可以从一种物体转移到另一种形式。

Think back to the leaf example. The leaf was hanging from a branch. At this time, it had gravitational potential energy. As it came loose from the branch, gravity pulled it toward the ground. The leaf started to fall, or move, toward the ground. Its potential energy was changed into motion. As it landed on the ground, it stopped moving. As it lays on the ground, it has no potential to move. If it does move it is because something else transferred energy to it. Perhaps the wind blew and lifted the leaf back into the air. Maybe a young child picked it up and then dropped it to watch it fall. It was the wind, or the child, that changed the position of the leaf to once again give it potential energy. 
::回想一下叶子的例子。叶子是从树枝上挂起的。此时叶子有引力潜能。当叶子从树枝上松开时,引力将叶子拉向地面。叶子开始掉落,或向地面移动。其潜在能量被改变为运动。当它落在地上时,它停止了移动。当它躺在地上时,它没有移动的潜力。如果它移动它是因为有其他东西将能量转移到树枝上。也许风吹了,把叶子拉回空气中。也许一个幼儿把它捡起来,然后扔到地上看着它坠落。是风,或者是孩子,它改变了叶子的位置,再次给了它潜在的能量。

Conservation of Energy (Advanced Topic)
::节能(高级专题)

You have probably heard the saying, "What goes up must come down." This is one way of explaining conservation. This same idea applies to energy. Potential and kinetic energy are always equal to the whole. As one type of energy increases, the other decreases. You never have more than you started with. You never have less, either. 
::你可能听过一句谚语,“上升的东西必须下降。”这是解释节能的一种方式。这个想法也适用于能源。潜能和动能总和整体一样。随着一种能源的增加,另一种能源的减少。你从未有过比原来多过。你也没有少过。同样,你也没有少过。

In some situations, energy can be used to overcome friction. In these cases, the energy is converted to heat. Have you ever rubbed your hands together to make them warm? That is a form of energy conservation. The energy of rubbing your hands together is not wasted. That energy is turned into heat energy.
::在某些情况下,能源可以用来克服摩擦。在这些情况下,能源被转换为热能。你们有没有用手抚摸过,以便暖和?这是一种节能形式。用手抚摸的能量不会浪费。能源被转换成热能。

Examples of Energy Conversions
::能源转换实例

There are many other examples of energy conversions between potential and kinetic energy. You can see this in   below showing the swing and trampoline. Can you think of other examples?
::潜力和动能之间的能源转换还有其他许多例子。 您可以在下面看到这个例子, 显示摇摆和蹦床。 您能想到其他的例子吗 ?

 

KQED: Make it at Home: Table-Top Linear Accelerator
::KQED: 在家制作: 表格- 桌面线性加速器

QUEST teams up with Make Magazine to construct a really cool device: a tabletop linear accelerator. This device demonstrates kinetic energy. It does so by shooting a steel ball.
::QUEST 团队与 Make Make Jazar 一起建造一个非常酷的设备: 一个桌面线性加速器。 这个设备展示动能。 它通过射击钢球来这样做 。

Lesson Summary
::经验教训摘要

• Energy is the ability to do work. When work is done, energy is transferred from one object to another. Energy can exist in different forms. Most forms of energy can also be classified as kinetic or potential energy.
  ::能源是工作的能力。当工作完成后,能源就会从一个物体转移到另一个物体。能源可以以不同的形式存在。大多数形式的能源也可以被归类为动能或潜在能源。

• Kinetic energy is the energy of motion. Things with kinetic energy can do work. Kinetic energy depends on an object’s mass and speed.
  ::动能是运动的能量。 有动能的东西可以发挥作用。 动能取决于物体的质量与速度。

• Potential energy is stored energy. It may be because of its position or shape. It includes gravitational potential energy and elastic potential energy. Gravitational potential energy depends on an object’s weight and height above the ground. Elastic energy depends on an object's ability to return to a normal shape after it is stretched or squeezed
  ::潜在能源是储有的能源,可能是因为其位置或形状,包括引力潜能能和弹性潜能能。重力潜能能取决于物体在地面上的重量和高度。高能取决于物体在被拉累或挤压后恢复正常形状的能力。

• Energy can be converted from one type or form of energy to another. Energy often changes between potential and kinetic energy. Energy is always conserved during energy conversions.
  ::能源可以从一种能源类型或形式转换为另一种能源。 潜在能源与动能之间经常发生变化。 在能源转换期间,能源总是得到节能。

Lesson Review Questions
::经验回顾问题

Recall
::回顾

1. Define kinetic energy and give an example.
   ::定义动能,举个例子。

1. What is potential energy?
   ::什么是潜在的能源?

1. Describe how energy changes on a swing.
   ::描述秋千的能量变化

Apply Concepts
::应用概念

4. Explain how energy changes in the spring toy below when it goes down stairs.
   

    
   
   ::解释下楼梯时 弹簧玩具的能量变化如何

Think Critically
::仔细仔细思考

5. How is energy related to work?
   ::能源与工作的关系如何?

5. Compare and contrast gravitational potential energy and elastic potential energy.
   ::对比和对比重力潜在能量和弹性潜在能量。

Points to Consider
::需要考虑的要点

The examples of kinetic and potential energy you read about in this lesson are types of mechanical energy. Mechanical energy is one of several forms of energy you can read about in the next lesson, "Forms of Energy."
::机械能源是下个课“能源的形式”中可以读到的几种能源形式之一。

• Based on the examples in this lesson, how would you define mechanical energy?
  ::根据这一教训中的例子,你会如何定义机械能源?

• What might be other examples of mechanical energy?
  ::机械能源的其他例子可能是什么?