शैडोइंग अभ्यास: How High Can Birds Fly? - वीडियो के साथ अंग्रेजी बोलना सीखें
अभ्यास मोड चुनें
हर मोड पूरी स्क्रीन का अभ्यास कक्ष खोलता है।
77 वाक्य
यदि वाक्य बहुत छोटे या लंबे हों, तो समायोजित करने के लिए Edit पर क्लिक करें।
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In 1973, an airliner struck a bird called a Rupel's Griffin vulture, which on its own isn't that weird.
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Planes hit birds pretty regularly during takeoffs and landings.
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But this collision happened at a cruising height of over 11,000 meters.
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That's way above the height at which most birds fly.
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Which makes me wonder, what is the highest a bird can actually fly?
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Hi, I'm Cameron and this is MinuteEarth.
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Birds don't tend to fly higher than they absolutely need to, for the same reason you You don't sprint when you could walk.
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It's difficult and tiring.
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So we can't necessarily get the answer to this question through observation.
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I mean, I guess we could drop a bunch of birds out of airplanes and see what happens, but our AdSense revenue definitely isn't going to cover that.
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Plus, we're not monsters.
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So let's use our understanding of aerodynamics, scaling laws, and biology to science our way to an approximate answer.
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There are two things that limit how high a bird can fly.
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Its ability to stay aloft as the air pressure decreases, and on a much more basic level, its ability to stay alive as the temperature and amount of oxygen decreases.
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So first, let's figure out which bird could survive at the highest altitude.
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Oxygen supplies birds the energy they need to stay warm, but at higher altitudes there's less oxygen available and the temperature is much colder,
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so a bird's ability to survive high up in the air depends on how efficiently they use oxygen
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and how well they can retain body heat paper measured the oxygen use of a handful of birds and found that, very generally, their overall oxygen use increases with mass.
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We can then adjust according to other traits, like how much energy their flight muscles require and how much insulation their feathers provide.
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From all of this, we can calculate the altitude at which each bird should suffer from hypothermia.
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Let's call this their popsicle point.
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If we then compile a data set of flying birds and plug their data into these equations, we can see a general pattern emerge.
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Larger birds can theoretically survive at higher altitudes than smaller birds.
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There are exceptions, of course, this is biology after all, but our calculations suggest that there are a bunch of birds that could potentially survive above 10,000 meters.
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And the largest bird in our dataset, the wandering albatross, might be able to survive as high as 17,000 meters.
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But remember, we also need to figure out if any of these birds could actually stay aloft at such high altitudes.
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Because the air is less dense the higher you go, less air is available at higher altitudes to push upward against a bird's wings and create that lift.
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A bird's ability to stay aloft high in the air depends on its weight, size of its wings, and the shape and angle of attack of its wings.
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That's a factor called the lift coefficient.
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Combining all of that tells us how much lift a bird's wings should generate in still air at a given altitude.
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Simple enough at first.
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But while weights and wingspans and whatnot are easy enough to measure, the wing shapes and angles aren't.
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Because a bird's wing shape changes as it flies.
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I'll save you the long explanation of my rationale here, and just say that this is about where I go out on a bit of a limb.
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The lift coefficient for the birds in our dataset peaks at about 1.5 or so, and that's when they're taking off or about to stall.
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In other words, when the bird is trying hardest to generate lift.
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And since staying aloft is likely a struggle at a bird's maximum altitude, this is probably a pretty good estimate of the lift coefficient at this point.
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From there, we can find the lowest air pressure at which each bird could generate sufficient lift to keep its mass aloft, and then use our friend the barometric equation to convert those
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numbers to altitudes to estimate the highest point each bird in our dataset should be able to actually maintain flight.
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Let's call this their lift limit.
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In general, the smaller birds have the highest lift limits.
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The hulking Muteswan would struggle to generate lift at a mere 3,800 meters, while the puny Sandmartin should be able to glide at nearly 19,000 meters.
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Of course, air moves and it's not uniformly dense at given altitudes, so there's definitely some wiggle room here, which will be a surprise tool that's going to help us later.
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But in any case, a bird with a higher lift limit should be able to fly higher than a bird with a lower one.
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Now let's combine our lift limit data with our popsicle point data.
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We can see that lots of birds, like the missile thrush, can theoretically fly super high, but would freeze long before they got there.
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And then there are a bunch of other birds, like the wandering albatross, that could likely survive at super high altitudes but wouldn't be able to actually maintain flight up there.
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That leaves us with a small cluster of birds with relatively high popsicle points and high lift limits.
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Mathematically, these should be the highest flying birds, and for the most part, they're geese.
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The greylag goose, the bean goose, the Canada goose, and the bar-headed goose should be able to fly as high as 8,000 meters or so,
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according to our calculations, and this matches up pretty well with what scientists have actually observed.
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Like during its migration over the highest mountain range on the planet, the bar-headed goose can reach altitudes of over 7,000 meters.
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Then there's the white stork, which based on its popsicle point and lift limit, is our predicted highest flying bird.
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It could potentially fly up to about 10,500 meters.
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In reality, it doesn't fly anywhere near that high.
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But remember, birds don't necessarily fly as high as they might be physically capable of.
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But wait, what about the Rupal's griffin?
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A bird we know for a fact can fly higher than 11,000 meters.
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Our math suggests that it is lift limited a lot lower than that, about 8200 meters.
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But this is where theoretical calculations fall short without some additional real-world knowledge.
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See, the RuPaul's Griffin likes to soar on thermals, warm columns of rising air that can help birds exceed their mathematical lift limit,
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sometimes even thousands of extra meters up into the air.
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Other birds are also known to ride thermals, but none of the other high popsicle point birds ride such supercharged thermals, so the Rupples Griffin is likely the bird capable of the highest flight,
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with the right thermal.
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It might even reach its very generous popsicle point of 15,000 meters.
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Turns out, that bird might have had a lot of climbing left to do.
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You might have noticed that this video is chock full of all sorts of calculations
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that I basically ripped my hair out trying to make sure I got right.
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It would have been great if I had a brilliant tutor sitting next to me guiding my learning.
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Wait, there is a brilliant tutor.
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and MinuteEarth's viewers can save an additional 20% off an annual subscription at Brilliant.org slash MinuteEarth.
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Thanks Brilliant!
ऐप डाउनलोड करें
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इस पाठ की शब्दावली और बोलने के सुझाव
इस वीडियो में शैडोइंग के लिए 77 वाक्य और 1297 शब्द हैं। बोला गया हिस्सा 6:44 लंबा है। वक्ता तेज़ बोलता है, लगभग 193 शब्द प्रति मिनट, इसलिए जुड़ी हुई और कमज़ोर ध्वनियाँ ज़्यादा मिलेंगी। केवल 79% शब्द अंग्रेज़ी के 3,000 सबसे आम शब्दों में से हैं, इसलिए शब्दावली कठिन है।
इस वीडियो की मुख्य शब्दावली
वीडियो के 15 सीखने लायक शब्द, उच्चारण और अर्थ के साथ:
| शब्द | उच्चारण | अर्थ |
|---|---|---|
| oxygen संज्ञा | /ˈɑksɪd͡ʒən/ | जारक, ऑक्सीजन |
| goose संज्ञा | /ɡus/ | हंस |
| generate क्रिया | /ˈd͡ʒɛn.ə.ɹeɪt/ | उपजाना |
| calculation संज्ञा | /ˌkælkjuˈleɪʃn̩/ | गणना, परिकलन |
| tutor संज्ञा | /ˈtjuːtəː/ | शिक्षक, शिक्षिका |
| necessarily क्रिया विशेषण | /ˌnɛs.əˈsɛɹ.ə.li/ | अवश्य, अनिवार्यतः |
| angle संज्ञा | /ˈæŋ.ɡəl/ | कोण |
| estimate संज्ञा | /ˈɛs.tɪ.mət/ | आकलन, अनुमान |
| biology संज्ञा | /baɪˈɑ.lə.d͡ʒi/ | जीवविज्ञान, जैविकी |
| decrease क्रिया | /dɪˈkɹiːs/ | घटना |
| mathematics संज्ञा | /mæθ(.ə)ˈmæt.ɪks/ | गणित, गणित-विधा |
| combine क्रिया | /kəmˈbaɪn/ | मिलाना |
| equation संज्ञा | /ɪˈkweɪ.ʒən/ | समीकरण |
| dense विशेषण | /ˈdɛns/ | घना |
| wander क्रिया | /ˈwɑndɚ/ | भटकना, घूमना |
वीडियो में आने वाली फ़्रेज़ल वर्ब
| शब्द | अर्थ |
|---|---|
| take off क्रिया | उतारना |
ध्यान देने योग्य उच्चारण
वक्ता 15 बार संक्षिप्त रूपों का प्रयोग करता है, जैसे don't, isn't, they're। इन्हें वैसे ही छोटा बोलें जैसा आप सुनते हैं।
- “th” की ध्वनियाँ: mathematics /mæθ(.ə)ˈmæt.ɪks/, mathematical /ˌmæθ(.ə)ˈmæt.ɪ.kəl/, thermal /ˈθɜːməl/, theoretical /ˌθi.əˈɹɛt.ɪ.kəl/, feather /ˈfɛðə/
- “sh” और “zh” की ध्वनियाँ: calculation /ˌkælkjuˈleɪʃn̩/, potentially /pəˈtɛnʃ(ə)li/, equation /ɪˈkweɪ.ʒən/, explanation /ˌɛkspləˈneɪʃən/, exception /əkˈsɛpʃən/
- लंबे शब्द — बलाघात सही रखें: necessarily /ˌnɛs.əˈsɛɹ.ə.li/, potentially /pəˈtɛnʃ(ə)li/, biology /baɪˈɑ.lə.d͡ʒi/, mathematics /mæθ(.ə)ˈmæt.ɪks/, explanation /ˌɛkspləˈneɪʃən/
इस वीडियो से अभ्यास कैसे करें
- पहले बिना बोले पूरा वीडियो एक बार सुनें और जो शब्द नहीं आते उन्हें लिख लें।
- 0.75× गति से शुरू करें, एक-एक वाक्य की शैडोइंग करें, और सहज लगने पर सामान्य गति पर लौटें।
- अपनी आवाज़ रिकॉर्ड करें और मूल से तुलना करें, ख़ासकर oxygen, goose, generate जैसे शब्दों पर ध्यान दें।
शैडोइंग तकनीक क्या है?
शैडोइंग (Shadowing) एक विज्ञान-समर्थित भाषा सीखने की तकनीक है जो मूल रूप से पेशेवर दुभाषिया प्रशिक्षण के लिए विकसित की गई थी। विधि सरल लेकिन शक्तिशाली है: आप मूल अंग्रेज़ी ऑडियो सुनते हैं और तुरंत इसे ज़ोर से दोहराते हैं — जैसे वक्ता की छाया 1-2 सेकंड की देरी से। शोध से पता चलता है कि यह उच्चारण सटीकता, स्वर, लय, जुड़ी हुई ध्वनियाँ, सुनने की समझ और बोलने की प्रवाहशीलता में काफ़ी सुधार करता है।