由于重力加速

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It’s a good thing this mountain climber’s safety gear is working, because it’s a long way down to the ground! If he were to fall, he’d be moving really fast by the time he got there. The higher any object starts falling from above Earth’s surface, the faster it’s traveling by the time it reaches the ground (assuming no air resistance). Do you know why? The reason is gravity.  
::幸好这个登山者的安全装备起作用了,因为离地面还有很长的路要走。 如果他摔倒了,那么他到那里时会动作非常快。 任何物体从地球表面上坠落的速度都越高,到达地面的速度越快(假设没有空气阻力 ) 。 你知道原因吗? 原因就是引力。

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Speeding up While Falling Down
::下降的同时加速前进

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Gravity is a force that pulls objects down toward the ground. When objects fall to the ground, gravity causes them to accelerate. is a change in , and velocity, in turn, is a measure of the and direction of motion. Gravity causes an object to fall toward the ground at a faster and faster velocity the longer the object falls. In fact, its velocity increases by 9.8 m/s2, so by 1 second after an object starts falling, its velocity is 9.8 m/s. By 2 seconds after it starts falling, its velocity is 19.6 m/s (9.8 m/s + 9.8 m/s), and so on. The acceleration of a falling object due to gravity is illustrated in the Figure . 
::引力是将物体拉向地面的一种力量。 当物体落到地面时, 引力会加速它们。 速度是运动的量度和方向。 引力使物体以较快和较快的速度坠落到地面, 事实上, 其速度会增加9. 8 m/ s2, 所以在物体开始坠落后, 速度会增加1秒, 速度是9. 8 m/s。 在物体开始坠落后2秒, 速度是19.6 m/s (9. 8 m/s+9. 8 m/s) 等。 图中显示了因重力而坠落的物体加速情况。

 

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For an object that has a constant acceleration, like an object falling due to gravity, we can calculate the acceleration using the following equation:
::对于一个具有恒定加速度的物体,就像一个因重力而坠落的物体,我们可以使用以下方程式计算加速度:

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$\begin{array}{r}a=\frac{\mathrm{\Delta }v}{t}\end{array}$
::avt (千瓦)

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Where a is the acceleration, ∆v is the change in velocity, and t is the time the object is accelerating. We can also rearrange this equation for ∆v and t:
::a 是加速度, v 是速度的变化, t 是天体加速的时间。 我们还可以重新排列此方程式的 v 和 t :

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$\begin{array}{r}t=\frac{\mathrm{\Delta }v}{a}\end{array}$
::塔瓦

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$\begin{array}{r}\mathrm{\Delta }v=a\times t\end{array}$
::v=axt

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Q : In this diagram, the boy drops the object at time t = 0 s. By t = 1 s, the object is falling at a velocity of 9.8 m/s. What is its velocity by t = 5 s? What will its velocity be at t = 6 s if it keeps falling?
::问题:在这个图表中,男孩在时间t = 0 s.t = 1 s.该物体正以9.8 m/s的速度坠落。t = 5 s.该物体的速度是多少?如果该物体继续坠落,其速度是多少?如果T = 6 s?

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A : Its velocity at t = 5 s can be calculated by multiplying the acceleration by the time:
::A:其 t = 5 秒的速度可以乘以加速度乘以下列时间计算:

 

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$\begin{array}{rlr}& \mathrm{\Delta }v=a\times t& \\ & \mathrm{\Delta }v=9.8m/s^2\times 5& \\ & \mathrm{\Delta }v=49.0m/s& \end{array}$
::*v=axxxv=9.8m/s2x5}v=49.0m/s *v=49.0m/s

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At t = 6 s, it will be 58.8 m/s (49.0 m/s + 9.8 m/s). 
::T = 6秒,为58.8米/秒(49.0米/秒+9.8米/秒)。

 

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Use the simulation below to further explore the  acceleration  of a cliff diver. Observe the relationship between position, velocity, and acceleration as the diver falls under the influence of gravity.
::使用下面的模拟来进一步探索悬崖潜水员的加速度。 当潜水员处于重力影响之下时, 观察位置、 速度和加速度之间的关系 。

 

 

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Mass and Acceleration Due to Gravity
::由于重力而质量和加速

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What if you were to drop a bowling ball and a  basket ball at the same time from the same above the ground? The bowling ball has greater mass than the basketball, so the pull of gravity on it is greater. Would it fall to the ground faster? No, the bowling ball and basketball would reach the ground at the same time. The reason? The more massive bowling ball is also harder to move because of its greater mass, so it ends up moving at the same acceleration as the basket ball. This is true of all falling objects. They all accelerate at the same rate due to gravity, unless air affects one object more than another. For example, a falling leaf is slowed down by air resistance more than a falling acorn because of the leaf’s greater surface area. 
::如果保龄球和篮球同时从地面上投下一个保龄球和篮球,会怎么样?保龄球的重量大于篮球,引力会更大。它会掉到地上更快吗?不,保龄球和篮球会同时落到地上。原因?保龄球由于质量更大,更大型的保龄球更难移动,因此它最终会以与篮球相同的加速速度前进。所有坠落的物体都是如此。它们都因重力而加速加速加速,除非空气对一个物体的影响大于另一个物体。例如,坠落的叶会因空气阻力而减慢,而不是因为叶的面积更大而跌落的角。

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Q : If a leaf and an acorn were to fall to the ground in the absence of air (that is, in a vacuum), how would this affect their acceleration due to gravity?
::问:如果没有空气(即在真空中),一片叶子和橡子倒在地上,那么,由于重力,这将如何影响加速?

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A : They would both accelerate at the same rate and reach the ground at the same time.
::A:它们将以同样的速度加速,并同时到达实地。

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Watch the video below to dispel some common misconceptions about falling objects:
::以下是影片, 以消除对落落物体的一些常见误解:

 

 

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Summary
::摘要

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• When gravity pulls objects toward the ground, it always causes them to accelerate at a rate of 9.8 m/s ² .
  ::当引力将物体引向地面时,它总是使物体加速速度达到9.8 m/s2。
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• Regardless of differences in mass, all objects accelerate at the same rate due to gravity unless air resistance affects one more than another.
  ::不论质量差异如何,所有物体均因重力而以相同速度加速加速,除非空气阻力影响不止一个物体。

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Review
::回顾

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1. Why do objects fall faster the longer they fall toward Earth?
   ::为什么天体落到地球的时间越长 落得越快?
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2. What is the rate of acceleration due to gravity?
   ::重力加速率是多少?
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3. How does mass affect acceleration due to gravity?
   ::质量如何因重力而影响加速?