13.1 工作
Section outline
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The kids in the picture on the left are having fun playing flag football. The teen in the picture on the right is working hard studying for an exam. It’s obvious who is doing work—or is it? Would it surprise you to learn that the kids who are working are the ones who are having fun playing football, while the teen who is studying isn’t doing any work at all? The reason why has to do with how work is defined in physics .
::左边的图片中的孩子玩得很开心。 右边的图片中的青少年正在努力学习考试。 很明显,谁在工作 — — 或者说谁在工作? 得知工作的孩子玩足球很愉快,而正在学习的青少年根本不在做任何工作,你会感到惊讶吗? 原因与物理学如何界定工作有关。Defining Work
::界定工作Work is defined differently in physics than in everyday language. In physics, work is the transferred when a force is applied to move an object over a . The kids who are playing football in the picture above are using force to move their bodies and the football, so they are doing work. The teen who is studying isn’t moving anything, so she isn’t doing work. Not all force that is used to move an object does work. For work to be done, the force must be applied in the same direction that the object moves. If a force is applied in a different direction than the object moves, no work is done. The Figure illustrates this point.
::物理学对工作的定义与日常语言不同。在物理学中,工作是当用一种力量将物体移到一个物体上时的工作转移。在上图中玩足球的孩子们正在用武力移动自己的身体和足球,所以他们正在工作。正在学习的青少年没有移动任何东西,所以她没有工作。并非所有用来移动物体的武力都起作用。要完成的工作,必须按物体移动的方向来应用。如果将一种力量应用到与物体移动不同的方向,则没有做任何工作。图说明了这一点。When the man lifts the box he must do work in the vertical direction. As he moves forward, no more work is done in the vertical direction. Q : If the box the man is carrying is very heavy, does he do any work to keep it raised as he walks across the room with it?
::问:如果这个男人携带的盒子非常沉重,他有没有做任何工作,在穿过房间时把它抬起来?A : Regardless of the of the box, the man does no work on to hold it while walking across the room. However, he does have to do some work to get the box moving in the horizontal direction.
::A:不管盒子的大小,男人在穿过房间时没有工作来握住它。然而,他确实必须做一些工作才能让盒子朝横向移动。Work, Force, and Distance
::工作、力量和距离Work is directly related to both the force applied to an object and the distance the object moves. It can be represented by the equation:
::工作与物体所应用的强度和物体移动的距离直接相关。Work = Force × Distance
::工作=力x距离This equation shows that the greater the force that is used to move an object or the farther the object is moved, the more work that is done.
::此方程式显示用于移动对象的力越大, 移动时间越远, 完成的工作就越多 。To see the effects of force and distance on work, compare the weight lifters in the Figure . The two weight lifters on the left are lifting the same amount of weight, but the one on the bottom is lifting the weight a greater distance. Therefore, this weight lifter is doing more work. The two weight lifters on the bottom right are both lifting the weight the same distance, but the weight lifter on the left is lifting a heavier weight, so she is doing more work.
::要看到力力和距离对工作的影响, 请比较图中的重量提升器。 左边的两个重量提升器举起的重量相同, 但底部的重量提升器举起的重量较大。 因此, 这个重量提升器正在做更多的工作。 右下角的两个重量提升器举起的重量相同, 但左边的重量提升器举起的重量较大, 所以她正在做更多的工作 。Watch the video below to learn more about the relationship between work and energy:
::更多了解工作与能源之间的关系:Summary
::摘要-
In physics, work is defined as the use of force to move an object. For work to be done, the force must be applied in the same direction that the object moves.
::在物理学中,工作的定义是使用武力移动物体,要完成工作,必须按物体移动的方向使用。 -
Work is directly related to both the force applied to an object and the distance the object moves. It can be represented by the equation: Work = Force × Distance.
::工作与对象的强度和物体移动的距离直接相关。可以用公式表示: 工作= 力x距离。
Review
::回顾-
How is work defined in physics?
::物理学如何界定工作? -
Write the equation that relates work to force and distance.
::写下有关工作与力量和距离的方程。 -
Assume that a friend hands you a heavy book to hold as he turns the combination lock on his locker. Which of you does more work?
::假设一个朋友把一本重书交给你 当他打开他柜子的锁锁时
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In physics, work is defined as the use of force to move an object. For work to be done, the force must be applied in the same direction that the object moves.
