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- I think it's time we
- 我想是時候我們
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the scientifically challenged and concentrate
科學挑戰者和集中
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on one of science's heroes, Tyler Bradt,
科學界的英雄之一,泰勒-布拉德特。
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kayaker extraordinaire.
皮划艇特級大師。
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He wants to kayak over this, Palouse Falls in Washington.
他想在華盛頓的帕盧茲瀑布上劃皮艇。
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Thousands of cubic feet of water pass over this fall
數千立方英尺的水從這個瀑布上流過。
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every second and drop 186 feet to the pool below.
每秒鐘都會下降186英尺到下面的游泳池。
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To consider kayaking over this, he must either
要考慮在這上面劃皮划艇,他必須要麼
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be a few sandwiches short of a picnic,
還差幾個三明治就可以去野餐了。
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or a world record breaker.
或打破世界紀錄的人。
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We hope.
我們希望:
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[music playing]
[音樂播放]
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Oh.
哦。
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There he is, the new world record
他在那裡,新的世界紀錄
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holder of one of the most dangerous stunts
霸王硬上弓
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I have ever seen.
我見過的。
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Needless to say, even if you do have a 186-foot water feature,
不用說,就算你真的有186英尺的水景。
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don't try this at home or anywhere else.
不要在家裡或其他地方嘗試這個。
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Falling off a waterfall is the easy part.
從瀑布上掉下來是很容易的事。
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But as gravity initially accelerates you down
但是,由於重力最初加速了你的下降
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at 32 feet per second per second,
以每秒32英尺的速度。
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it's surviving that's the tricky bit.
它的生存,是棘手的位。
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Our kayaker must go over the falls at the correct speed
我們的皮划艇必須以正確的速度越過瀑布。
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to give gravity just enough time to generate
給予引力足夠的時間來產生
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the angular velocity needed to rotate the kayak 90 degrees.
將皮艇旋轉90度所需的角速度。
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This angle minimizes hydrodynamic drag,
這個角度可以使流體動力阻力最小化。
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so he experiences less impact force
所以他受到的衝擊力較小
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and cuts through the water.
並切開水面。
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It's also worth noting that a kayak's stability is
值得注意的是,皮划艇的穩定性在於
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dependent on keeping the center of mass
依賴於保持品質中心
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in line with the center of buoyancy,
與浮力中心一致。
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which is in the middle of a submerged volume.
處於淹沒的體積之中。
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Otherwise.
不然的話
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OK.
好的
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Science-taught, let's see if our team of want-to-be record
理科出身的我們看看我們的團隊是否想創下
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breakers have learned.
斷者已經瞭解到。
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He's practicing the science with a man-made kind of waterfall,
他在用一種人造的瀑布來實踐科學。
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but the law of gravity is the same.
但萬有引力定律是一樣的。
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The thin layer of water acting as a lubricant
作為潤滑劑的薄層水
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combined with the steep angle allows gravity to do its thing.
再加上陡峭的角度,讓重力發揮其作用。
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It's not quite the 32 feet per second
還沒有達到每秒32英尺的速度。
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per second of a waterfall freefall,
每秒鐘的瀑布自由落體。
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but he's only practicing.
但他只是在練習。
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On to angular velocity, or in this case, the lack of it.
說到角速度,或者在這種情況下,沒有角速度。
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Launching too fast meant he gained very little angular
發射速度太快,意味著他獲得的角度非常小。
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velocity, hitting H2O at a terrible angle,
速度,以可怕的角度撞擊H2O。
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thereby maximizing hydrodynamic drag.
從而最大限度地提高流體動力阻力。
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Which is bad, as it brought him to an almost immediate and very
這是不好的,因為這給他帶來了一個幾乎是直接的,非常的
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painful stop.
痛苦的停止。
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Waterfall.
瀑布。
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Check.
檢查。
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Angular velocity.
角速度。
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Check.
檢查。
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Stability.
穩定性;
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Check, ish.
檢查,是的。
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It's an upside down check, but technically he still got
這是一個顛倒的檢查,但技術上他仍然得到了。
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himself into a stable position.
自己進入了一個穩定的位置。
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It's just a shame his center of mass
只可惜他的品質中心位置
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is directly below his center of buoyancy,
是在他浮力中心的正下方。
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as his head is the thing he uses to breathe.
因為他的頭是他用來呼吸的東西。
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Cheering without acknowledging the person
歡呼,卻不承認這個人
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that just saved your life.
這只是救了你的命。
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Check.
檢查。
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Even if our want-to-be record breakers do get to grips
即使我們想打破紀錄的人也能掌握住。
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with angular velocity, hydrodynamic drag,
與角速度、流體動力阻力。
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and stability, like Tyler did, 186 feet is just too dangerous.
和穩定性,就像泰勒那樣,186英尺實在是太危險了。
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Maybe it's better to kayak somewhere safer, like a puddle.
也許在安全的地方劃皮艇比較好,比如水坑。