重重

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Astronauts in training often fly in the KC-135 training aircraft to experience near-weightlessness. Three Japan Aerospace Exploration Agency astronauts—Akihiko Hoshide, Satoshi Furukawa, and Naoko Yamazaki—are shown here during such an exercise. Though they experience near-weightlessness, we can see that their mass has not changed. What is the relationship between mass and weight?
::参加培训的宇航员常常在KC-135训练飞机上飞行,以体验近乎体重不足的经历。 在这次演习中,有三名日本宇宙航空研究开发机构的宇航员,Akihiko Hoshide、Satoshi Furukawa和Naoko Yamazaki在这里展示。 虽然他们经历近体重不足的经历,但我们可以看到他们的质量并没有改变。 质量和体重之间的关系是什么?

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Mass and Weight
::重量和重量

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The mass of an object is defined as the amount of matter in the object. The amount of mass an object has does not change; a moon rock that has been returned to Earth has the same mass on the Earth’s surface as it had on the moon. The amount of mass in an object is measured by comparing the object to known masses on an instrument called a balance.
::物体的质量被定义为物体中物质的数量。 物体的质量没有变化; 返回地球的月球岩石在地球表面的重量与在月球上的重量相同。 物体中的质量量是通过比较物体与已知质量的比较来衡量的,该物体在称为平衡的仪器上是已知质量的。

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Using the balance shown here, the object would be placed in one pan and known masses would be placed in the other pan until the pans were exactly balanced. When balanced, the mass of the object would be equal to the sum of the known masses in the other pan. A balance will work in any location; whether on the moon or on Earth, the moon rock mentioned earlier will have the same mass.
::使用此处显示的平衡, 对象将被放置在一个锅里, 已知质量将被放置在另一个锅里, 直到锅里完全平衡。 当平衡时, 对象的质量将等于另一锅里已知质量的总和。 平衡将在任何地点起作用; 无论在月球上还是在地球上, 前面提到的月球岩石都具有相同的质量 。

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The weight of an object is the force pulling the object downward. On Earth, this would be the gravitational force of the Earth on the object. On the moon, this would be the gravitational force of the moon on the object. The gravitational force of the moon is one-sixth the magnitude of the gravitational force of the Earth; the weight of the moon rock on the moon will be one-sixth the weight of the moon rock on the Earth’s surface.
::物体的重量是将物体向下拉动的力量。在地球上,这将是地球在物体上的引力。在月球上,这将是月球在物体上的引力。月球的引力是地球引力的六分之一;月球岩石在月球上的重量将是月球岩石在地球表面的重量的六分之一。

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The gravitational force is derived from Newton’s Second Law ,  F = ma , where  F is the force of gravity in Newtons,  m is the mass of the object in kilograms, and  a is the on Earth, 9.81 m/s ²   . When the formula is used specifically to solve for the weight of an object, it appears as  W = mg . Weight is always measured in force units Newtons, m is the mass of the object in kilograms, and g is the gravitational strength on the planet in N/kg or m/s ² (g _Earth = 9.81 m/s ² ).
::引力来源于牛顿的《第二法》F=ma,其中F是牛顿的重力,m是物体的重量(公斤),而a是地球上的重量(9.81 m/s2)。当公式用于具体解决物体重量时,它看起来是W=mg。重量总是用力单位牛顿测量,m是物体的重量(公斤),g是地球的重力(牛顿),g是N/kg或m/s2(地球=9.81 m/s2)。

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Gain access to an Astronaut Training Chamber in the simulation below and observe how the mass of an object on various planets stays the same but its weight (or force due to gravity) differs. Try to use the graph to derive the strength of the gravitational field on the moon, Mars and even Saturn’s moon, Dione!
::在以下模拟中进入宇航员训练厅,观察不同行星上物体的质量如何保持相同,但其重量(或因重力产生的力)不同。 尝试使用图表来得出月球、火星甚至土星月球(Dione)的引力场的强度!

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Examples
::实例

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Example 1
::例1

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What is the weight of an object sitting on the Earth’s surface if the mass of the object is 43.7 kg?
::如果物体的质量为43.7公斤,那么物体在地球表面的重量是多少?

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$\begin{array}{r}W=mg=(43.7\text{kg})(9.81{\text{m/s}}^2)=429\text{N}\end{array}$
::W=mg=(43.7公斤)(9.81 m/s2)=429 N

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Example 2  
::例2

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What is the mass of an object whose weight sitting on the Earth is 2570 N?
::地球重量为2570N的物体的质量是多少?

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$\begin{array}{r}m=\frac{W}{g}=\frac{2570\text{N}}{9.81{\text{m/s}}^2}=262\text{kg}\end{array}$
::m=Wg=2570 N9.81 m/s2=262公斤

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Further Reading
::继续阅读

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Summary
::摘要

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• The mass of an object is measured in kilograms and is defined as the amount of matter in an object.
  ::物体的质量以公斤计量,定义为物体中物质的数量。
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• Mass is determined by comparing an object to known masses on a balance.
  ::质量是通过比较物体与已知质量之间的平衡来确定的。
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• The weight of an object on the Earth is defined as the force acting on the object by the Earth’s gravity.
  ::地球上物体的重量被定义为地球引力在物体上作用的力量。
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• Weight is measured by a calibrated spring scale.
  ::重量由经校准的春季比例尺测量。
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• The formula relating mass and weight is $\begin{array}{r}W=mg\end{array}$ .
  ::相关质量和重量的公式为W=mg。

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Review
::回顾

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1. The mass of an object on the Earth is 100. kg.
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   1. What is the weight of the object on the Earth?
      ::地球上物体的重量是多少?
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   2. What is the mass of the object on the moon?
      ::月球上物体的质量是多少?
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   3. Assuming the acceleration due to gravity on the moon is exactly one-sixth of the acceleration due to gravity on Earth, what is the weight of the object on the moon?
      ::假设月球重力造成的加速度 与地球重力造成的加速度的六分之一, 月球上物体的重量是多少?
   
   ::地球上的物体质量是100公斤。 地球上物体的重量是多少? 月球上物体的重量是多少? 假设月球重力导致的加速度是地球重力导致的加速度的六分之一, 月球上物体的重量是多少?
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2. A man standing on the Earth can exert the same force with his legs as when he is standing on the moon. We know that the mass of the man is the same on the Earth and the moon. We also know that $\begin{array}{r}F=ma\end{array}$ is true on both the Earth and the moon. Will the man be able to jump higher on the moon than the Earth? Why or why not?
   ::站在地球上的人可以用他的双腿来施加同样的力力力,犹如站在月球上一样。 我们知道人的质量在地球和月球上是一样的。我们也知道F=ma在地球和月球上都是真实的。人能跳上月球比地球高吗?为什么不行呢?

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Explore More
::探索更多

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Use the resource below to answer the questions that follow.
::利用以下资源回答以下问题。

 

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1. What is  the  difference between mass and weight?
   ::质量和重量之间有什么区别?