10.6 重力
Section outline
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Long, long ago, when the universe was still young, an incredible force caused dust and particles to pull together to form the objects in our solar system. From the smallest moon to our enormous sun, this force created not only our solar system, but all the solar systems in all the galaxies of the universe. The force is gravity.
::很久很久以前,当宇宙还年轻的时候, 一种不可思议的力量使尘埃和粒子聚集在一起 形成太阳系中的物体。从最小的月亮到巨大的太阳, 这场力量不仅创造了我们的太阳系, 也创造了宇宙所有星系中的所有太阳系。 力量就是引力。Defining Gravity
::重力定义Gravity has traditionally been defined as a force of attraction between things that have mass. According to this conception of gravity, anything that has mass, no matter how small, exerts gravity on other matter. Gravity can act between objects that are not even touching. In fact, gravity can act over very long distances. However, the farther two objects are from each other, the weaker is the force of gravity between them. Less massive objects also have less gravity than more massive objects.
::重力传统上被定义为具有质量的物体之间的吸引力。 根据这种重力概念, 任何具有质量的物体, 无论多么小, 都可以对其它物质产生重力。 重力可以在甚至不触动的物体之间发生作用。 事实上, 重力可以在非常长的距离内发生作用。 但是, 距离越远的两个物体, 就越弱的物体是它们之间的重力。 较小的大型物体的重力也比大物体的重力要小。Earth’s Gravity
::地球的重力You are already very familiar with Earth’s gravity. It constantly pulls you toward the center of the planet. It prevents you and everything else on Earth from being flung out into space as the planet spins on its axis. It also pulls objects that are above the surface—from meteors to skydivers—down to the ground. Gravity between Earth and the moon and between Earth and artificial satellites keeps all these objects circling around Earth. Gravity also keeps Earth and the other planets moving around the much more massive sun.
::您已经非常熟悉地球的引力。 它不断将您拉向行星的中心。 它阻止您和地球上的其他人在行星旋转轴轴时被抛入太空。 它还将地表之上的物体从陨石到天体向下拖到地上。 地球和月亮之间的重力以及地球和人造卫星之间的重力使所有这些物体环绕地球。 重力也使地球和其他行星绕着大太阳运行。Q : There is a force of gravity between Earth and you and also between you and all the objects around you. When you drop a paper clip, why doesn’t it fall toward you instead of toward Earth?
::问题:地球和你之间,还有你和周围所有物体之间的重力。当你扔下一个纸片片时,为什么它不是落在地球身上,而是落在你身上呢?A : Earth is so much more massive than you that its gravitational pull on the paper clip is immensely greater.
::A:地球比你们大得多 以至于它的引力在纸片上的拉动 更大得多。Gravity and Weight
::重重和重重measures the force of gravity pulling downward on an object. The SI unit for weight, like other forces, is the Newton (N). On Earth, a mass of 1 kilogram has a weight of about 10 Newtons because of the pull of Earth’s gravity. On the moon, which has less gravity, the same mass would weigh less. Weight is measured with a scale, like the spring scale shown in the Figure . The scale measures the force with which gravity pulls an object downward.
::测量重力向下拉动物体的引力。 与其它力量一样, SI重力单位是牛顿( N) 。 在地球上, 1公斤的重量因地球引力的拉动而大约为10牛顿。 在月球上, 重力较小, 重力也较小。 体重用比例尺测量, 如图中显示的春季比例尺。 比例尺测量引力向下拉动物体的力。Watch the video below to learn more about gravity and factors that influence the strength of gravity between two objects:
::观看下面的视频,以了解更多影响两个物体之间重力的重力和因素:Summary
::摘要-
Gravity has traditionally been defined as a force of attraction between things that have mass. The strength of gravity between two objects depends on their mass and their distance apart.
::重力传统上被定义为具有质量的物体之间的一种吸引力。 两个物体之间的重力强度取决于它们的质量及其距离的距离。 -
Earth’s gravity constantly pulls matter toward the center of the planet. It also keeps moons and satellites orbiting Earth and Earth orbiting the sun.
::地球的引力不断将物质引向行星的中心。 它还使卫星和卫星绕地球和地球绕太阳绕地球运行。 -
Weight measures the force of gravity pulling on an object. The SI unit for weight is the Newton (N).
::重量单位为牛顿(N)。
Vocabulary
::词汇表-
What is the traditional definition of gravity?
::重力的传统定义是什么? -
Identify factors that influence the strength of gravity between two objects.
::查明影响两个物体之间重力的因素。 -
Define weight. What is the SI unit for weight?
::确定重量。 -
Explain why an astronaut would weigh less on the moon than on Earth.
::解释为什么宇航员对月球的重量会比对地球的重量要小
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Gravity has traditionally been defined as a force of attraction between things that have mass. The strength of gravity between two objects depends on their mass and their distance apart.
