Section outline

  • General

    Collapse all Expand all

  • 潜在能源

    A diver poised on a diving board above a pool, preparing to jump.

    This diver has just jumped up from the end of the diving board. After he dives and is falling toward the water, he’ll have , also known as the of moving matter. But even as he momentarily pauses before jumping high above the water, he has energy. Do you know why?
    ::这名潜水员刚刚从潜水板的尽头跳了下来。在潜水后,他正在向水倾斜,他将拥有,也被称为移动物质。 但是,即使他在跳上水前短暂停顿下来,他也有能量。 你知道原因吗?

    Stored Energy
    ::存储能源

    The diver has energy because of his position high above the pool. The type of energy he has is called potential energy. Potential energy is energy that is stored in a person or object. The person or object often has potential energy because of its position compared to something else or shape.
    ::潜水员之所以有能量,是因为身高高在水池上方。他所拥有的能量类型被称为潜在能量。潜在的能量是储存在人或物体中的能量。人或物体由于与其他物体或形状相比,其位置或形状往往具有潜在的能量。

    Q: What is it about the diver’s position that gives her potential energy?
    ::问:潜水员的立场给了她潜在的能量,

    A: Because the diver is high above the water, he has the potential to fall toward Earth because of gravity. This gives him potential energy.
    ::A:因为潜水员高度高于水面, 他有可能因为重力而掉向地球。这给了他潜在的能量。

    Gravitational Potential Energy
    ::重力潜能能源

    Potential energy due to the position of an object above Earth’s surface is called gravitational potential energy. Like the diver on the diving board, anything that is raised up above Earth’s surface has the potential to fall because of gravity. You can see another example of people with gravitational potential energy in the Figure . 
    ::地球表面上方的物体位置造成的潜在能量被称为引力潜在能量。 与潜水板上的潜水员一样,在地球表面上方升起的任何能量都有可能因引力而下降。 你可以看到图中另一个具有引力潜在能量的人的例子。

    A gymnast on a balance beam and a child sledding down a snowy hill.

    Gravitational potential energy depends on an object’s and its height above the ground. It can be calculated with the equation:
    ::引力潜在能量取决于物体及其在地面上的高度。

    Gravitational potential energy (GPE) = weight × height
    ::重力潜能能(GPE) = 重量x高度

    Consider the little child on the sled, pictured in the Figure . They weigh 140 newtons, and the top of the hill is 4 meters higher than the bottom. As they sit at the top of the hill, the child’s gravitational potential energy is:
    ::想象一下在雪橇上的孩子,在图中描绘。他们体重140牛顿,山顶比山底高4米。 当他们坐在山顶时,孩子的重力潜力是:

    GPE = 140 N × 4 m = 560 N • m
    ::GPE = 140 N × 4 m = 560 N = m

    Notice that the answer is given in newton meters (N • m), which is the SI unit for energy. A newton meter is the energy needed to move a weight of 1 newton over a of 1 meter. A newton meter is also called a joule (J).
    ::注意答案以牛顿计数( N ) m 表示, 牛顿计数( N ) 是 SI 能量单位。 牛顿计数是将重量为 1 牛顿的能量移动到 1 公尺以上所需的能量。 牛顿计也称为 焦耳( J ) 。

    Q: The gymnast on the balance beam pictured in the Figure weighs 360 newtons. What is the gymnast's gravitational potential energy if the balance beam is 1.2 meters above the ground?
    ::问题:在图中所描绘的平衡波束上的体操运动员体重为360牛顿。如果平衡波束高于地面1.2米,体操运动员的引力潜力是什么?

    A: Her gravitational potential energy is:
    ::A:她的引力潜能能量是:

    GPE = 360 N × 1.2 m = 432 N • m, or 432 J
    ::GPE = 360 N × 1.2 m = 432 N = m, 或 432 J

     

     

    Elastic Potential Energy
    ::弹性潜能能源

    Potential energy due to an object’s shape is called elastic potential energy. This energy results when an elastic object is stretched or compressed by a force. The farther the object is stretched or compressed, the greater its potential energy is. A point will be reached when the object can’t be stretched or compressed anymore. When the external force is removed, it will forcefully return to its original shape.
    ::由物体形状造成的潜在能量被称为弹性潜在能量。 当弹性物体被力拉拉或压缩时,这种能量产生结果。 物体越是拉拉或压缩,其潜在能量就越大。 当物体无法再拉拉或压缩时,就会达到一个点。 当外部力量被移走时,它将被迫恢复到原来的形状。

    Look at the pogo stick in the Figure . Its spring gains elastic potential energy when it is pressed down by the boy's weight. Moments after the boy jumps, his weight is no longer compressing the spring and it will spring back to its original shape. The energy it releases will push the pogo stick—and the boy—off the ground.
    ::看着图中的松果棒。它春季在被男孩的体重压压压时获得弹性的潜在能量。 男孩跳跃后,他的重量不再压缩弹簧,它会回到原来的形状。 它释放的能量将把松果棒——和男孩——推离地面。

    A boy on a pogo stick compresses the spring, demonstrating elastic potential energy.

    Q: The girl in the Figure is giving the elastic band of her slingshot potential energy by stretching it. She’s holding a small stone against the stretched band. What will happen when she releases the band?
    ::问题:图中的女孩正在通过伸展弹弓来提供其弹弓潜在能量的弹性带。 她拿着一块小石头对着拉伸的弹弓。 当她释放弹弓时会发生什么?

    A: The elastic band will spring back to its original shape. When that happens, watch out! Some of the band’s elastic potential energy will be transferred to the stone, which will go flying through the air.
    ::A:弹性带将回到原来的形状。 当发生这种情况时,当心!乐队的弹性潜在能量将转移到石头上,石头将飞过空中。

    A girl stretches a slingshot's band, preparing to launch a small stone.

    Other Forms of Potential Energy
    ::其他形式的潜在能源

    All of the examples of potential energy described above involve movement or the potential to move. The form of energy that involves movement is called mechanical energy . Other also involve potential energy, including chemical energy and nuclear energy . Chemical energy is stored in the bonds between the atoms of compounds. For example, food and batteries both contain chemical energy. Nuclear energy is stored in the nuclei of atoms because of the strong forces that hold the nucleus together. Nuclei of radioactive such as uranium are unstable, so they break apart and release the stored energy.
    ::上述所有潜在能源的例子都涉及移动或移动潜力,涉及移动的能源形式称为机械能源,其他也涉及潜在能源,包括化学能源和核能,化学能源储存在化合物原子之间的介质中,例如,粮食和电池都含有化学能源,核能储存在原子核心中,因为原子核的强大力量将核聚在一起,铀等放射性核心是不稳定的,因此它们分解并释放了储存的能源。

     

     

    Summary
    ::摘要

    • Potential energy is energy that is stored in a person or object.
      ::潜在能量是储存在人或物体中的能量。
    • Gravitational potential energy is due to the position of an object above Earth’s surface. The object has the potential to fall due to gravity. Gravitational potential energy depends on an object’s weight and its height above the ground (GPE = weight x height).
      ::引力潜在能量是由于一个物体在地球表面的方位。该物体有可能因引力而坠落。引力潜在能量取决于物体的重量及其在地面上的高度(GPE=重量x高度)。
    • Elastic potential energy is due to an object’s shape. It results when an elastic object is stretched or compressed. The more it is stretched or compressed, the greater its elastic potential energy is.
      ::弹性潜力能量是由物体的形状决定的。它的结果是弹性物体被拉长或压缩。它被拉长或压缩的程度越大,弹性潜力能量就越大。
    • Chemical energy and nuclear energy are other forms of potential energy.
      ::化学能源和核能是其他形式的潜在能源。

    Review
    ::回顾

    1. What is potential energy?
      ::什么是潜在的能源?
    2. Compare and contrast gravitational and elastic potential energy, and give an example of each.
      ::比较和对比引力和弹性潜在能量 并举一个例子
    3. The diver on the diving board in the opening picture weighs 500 Newtons. The diving board is 5 meters above the ground. What is the diver’s gravitational potential energy?
      ::在开张的图片中,潜水板上的潜水员体重为500牛顿。潜水板离地面5米。潜水员的引力潜力是什么?
    4. Why does food have potential energy?
      ::为什么食物有潜在的能量?