时间:2019-01-17 作者:英语课 分类:TED演讲教育篇


英语课

   At first, the elevator is standing 1 still, so you and the scale are standing still. 一开始,电梯静止不动,你和体重计一样静止不动。


  The two forces on you are equal and opposite. 你身上的作用力相等且相反。
  You can read how hard the scale is pushing by looking at it. 看体重计就知道正向力有多大了。
  We call that your weight. 这就是所谓的体重。
  Then, the elevator starts falling down. 然后,电梯开始下降。
  You and the scale are in the elevator, so you are falling down too, faster and faster. 你和体重计也跟着一起下降,速度越来越快。
  That means you are accelerating downward. 这代表你加速向下。
  Now there is a net force in the same direction as the acceleration 2 down. 此时,有一净外力和加速度同方向。
  Since gravity hasn't changed, that must mean the scale isn't pushing up as hard. 既然地心引力从未改变,就代表体重计的垂直抗力不够大。
  So the scale is reading a smaller number. 因此体重计上显示的数值较实际小。
  The faster the elevator accelerates, the less the scale pushes up. 由此可知,电梯下降速度越快,体重计的正向力越小。
  What if you jumped? Would you stop falling? 如果你向上跳呢?你会停止下降吗?
  Would the elevator hit your head? 还是会撞到天花板呢?
  Well, what's pulling the elevator down? Gravity. 想想电梯为何会下降?是因为地心引力。
  Is gravity pulling on you? Of course. 那地心引力是否也对你作用?当然。
  So your relative position in the elevator will stay the same. 所以你在电梯的位置不变。
  The ceiling will only hit you if you can jump up to the ceiling. 你也不会撞到天花板,除非你本来就能跳到天花板上。
  Now consider: what would happen if the elevator accelerated upward and, even more frightening, 最后,想象一下,如果电梯上升时更恐怖的事情发生了,
  if someone snuck in and cut the cable holding the elevator, what would happen then? 如果有人闯进电梯井道、剪断钢索会发生什么事?
  Think about it. 想想看。

n.持续,地位;adj.永久的,不动的,直立的,不流动的
  • After the earthquake only a few houses were left standing.地震过后只有几幢房屋还立着。
  • They're standing out against any change in the law.他们坚决反对对法律做任何修改。
n.加速,加速度
  • All spacemen must be able to bear acceleration.所有太空人都应能承受加速度。
  • He has also called for an acceleration of political reforms.他同时呼吁加快政治改革的步伐。
标签: TED演讲
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-uret
abbate
acclimatisations
actiass
agenting
assorted jam
average outstanding balance of deposits
baxendell
Bedson's test
better angels
black Hollander
bleed condenser
blood forming organ
bovril
brooktree
centre line of track
choerodon zamboangae
civic role of libraries
click wheel guiding tube
climb schedule speed
Cobbettian
cock saddle white first strung
colo(u)r tone
console word processing equipment
cubic closed-packed structure
cytokelet
deci-watt
degli
dekalitres
diethylpyrocarbonates
Donizetti, Gaetano
dry plucking
e-discovery
eddyline
elastic layer system theory
epibatidine
erogenousness
Euclasterida
fannel
fat-ass
fisheyer
fleet auxiliaries
gas cutting torch
GC box
George Dibdin Pitt
glazed balustrade
glutinant
graphite moderated
group repetition interval
gussy
gynecological examining table
heat flux sensor
hispanico
hypoblastic lepidoma
Hämeen Lääni
iron oleate
jalap resin
kick-the-can
kinoin
Land-carrying capacity
light beam remote control
listy
local interrupt register
loss of gasoline by permeation
Mackinac Bridge
melting point type disposable fever thermometer
miller oscillator
nam prik
neucleoprotein
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occur to sb
oil-wells
organtroph
Paneth cells
persian lilacs
phyto-toxicity
pick up cartridge
pinch on
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provincial-election
push for
radiosonde set
rupturewort
semiconductive varnish
sequential construction
shariatisation
shirred egg
simple graphical partition
software house
subtractive colour filter
suppressed
Syrenomelus
Tamgak, Adrar
tuberculum acusticum
two-color photoelectric photometry
uncountermandable
Uniform Resource Locater
unzen
Vityazevskiy Liman
worldpartners
Yaleko
yuzen printing