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  • General

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  • 投射动作

    An archer aiming above the bull's eye at a target in an indoor archery range.

    The archer in the opening image is aiming her arrow a little bit above the bull’s eye of the target, rather than directly at it. Why doesn’t she aim at the bull’s eye instead? The answer is projectile motion.
    ::开阔图像中的弓箭手正在瞄准她的箭头,略高于靶子的公牛眼睛,而不是直接瞄准目标。 她为什么不瞄准公牛的眼睛呢?答案是投弹动作。

    Combining Forces
    ::联合部队

    When the archer releases the bowstring, the arrow will be flung forward toward the top of the target where she’s aiming. But another force will also act on the arrow in a different direction. The other force is gravity, and it will pull the arrow down toward Earth. The two forces combined will cause the arrow to move in the curved path shown in the Figure . This type of motion is called projectile motion . It occurs whenever an object curves down toward the ground because it has both a horizontal force and the downward force of gravity acting on it.
    ::当弓箭手放出弓纹时,箭头将往向她瞄准的目标顶部。但另一支力量也将向另一方向对箭头采取行动。另一支力量是引力,它将把箭头向下拉向地球。两支力量将促使箭头在图中显示的弯曲路径中移动。这种运动被称为投射动作。当物体向地向下弯曲时,它就会发生,因为它具有水平力和向下引力。

    An archer aims at a target, illustrating projectile motion and the effect of gravity.

    Because of projectile motion, to hit the bull’s eye of a target with an arrow, you actually have to aim for a spot above the bull’s eye. You can see in the  Figure what happens if you aim at the bull’s eye instead of above it.
    ::由于投弹动作,用箭射中目标的公牛眼睛,你实际上必须瞄准公牛眼睛上方的某个地方。 图表中可以看到,如果瞄准公牛眼睛而不是它上方,会发生什么情况。

    A person aiming a bow at a target, illustrating projectile motion principles in archery.

    Launch the Archery SIM below to further explore the projectile motion of a bow on its path to hitting a target:
    ::进一步探索弓在射入目标的道路上的射线动画:

     

     

    Another Example of Projectile Motion
    ::另一个投射动作示例

    You can probably think of other examples of projectile motion. One is shown in the Figure . The cannon shoots a ball straight ahead, giving it horizontal motion. At the same time, gravity pulls the ball down toward the ground.
    ::您也许可以想到其他投弹动作的例子。 图中显示一个。 大炮直向前方发射球, 并给予它水平运动。 同时, 引力将球拉向地面 。

    Graph showing projectile motion of a cannon ball affected by gravity.

    Q : How would you show the force of gravity on the cannon ball in the Figure ?
    ::问题:你如何在图中显示大炮球的重力?

    A : You would add a line pointing straight down from the cannon to the ground.
    ::A:你会增加一条线, 从大炮直直直向地。

    Watch the video below to learn more about projectile motion:
    ::观看下面的影片, 了解更多有关射弹动作的影片:

     

     

    Summary
    ::摘要

    • Projectile motion is movement of an object in a curved path toward the ground because it has both a horizontal force and the downward force of gravity acting on it.
      ::投影运动是物体在向地面的弯曲路径中移动,因为它既具有水平力,又具有向下引力。
    • Examples of objects that have projectile motion include arrows and cannon balls.
      ::有射弹动作的物体的例子包括箭头和大炮球。

    Review
    ::回顾

    1. What is projectile motion? When does it occur?
      ::什么是投弹动作 什么时候发生
    2. How might knowledge of projectile motion help you shoot baskets in basketball?
      ::如何了解投弹运动 帮助你在篮球中射击篮子?