Pratique du Shadowing: How To Clear Icy Roads, With Science - Apprendre l'anglais à l'oral avec la vidéo
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Navigating an icy road can be pretty dangerous.
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And while applying a coating of salt is the time -tested method for rendering a frozen highway drivable, that salt has major downsides.
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It's toxic for plants, wildlife, and freshwater ecosystems.
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It contaminates our drinking water and air quality.
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It can even damage our cars, which feels a bit counterproductive.
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So how do we make winter roads safe for both drivers and the environment?
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Well, science says we have options.
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Salting a road is by far the most common de -icing technique.
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When salt mixes with water, the resulting solution has a lower freezing temperature than water by itself.
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However, this is true for all kinds of solutions, not just salty ones.
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Thanks to a scientific principle called freezing point depression,
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the temperature at which plain H2O freezes is always higher than its freezing point when something is dissolved into it.
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Essentially, the salt keeps water molecules from forming solid ice crystals because the salt interrupts the watery ice structure.
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The temperature at which the salty water eventually freezes depends on how salty the solution is.
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And although salting roads with the classic sodium chloride is effective, it wreaks havoc on plants and wildlife, contributes to poor air, soil,
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and water quality, ruins infrastructure like water treatment plants and bridges, and corrodes our stuff, like the steel in cars.
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Which is why some places are experimenting with a few solutions to this chili conundrum.
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We can start simple.
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Even a different kind of salt can make a difference.
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The sodium chloride you put on your food is chemically the same as the rock salt
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or halite that's spread on roads to melt ice.
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It's cheap, effective, and the infrastructure for delivering it to roads is already in place.
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The problem is that the chlorides in the sodium chloride don't ever break down in the environment.
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But other salts are better for the environment, if only
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because less is required in solution to achieve the same freezing point depression we get with a higher concentration of sodium chloride.
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Remember, a salt is just any compound that has positive and negative ions, which together make a neutral charge.
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There are a lot of options for what salts you can use.
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For instance, magnesium chloride and calcium chloride lower the freezing point more effectively due to some interesting chemistry.
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When sodium chloride dissolves in water, it dissociates into two ions, Na -plus and Cl -minus.
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Magnesium chloride and calcium chloride, on the other hand,
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dissociate into three ions each since they're each made of three total atoms instead of the two in NaCl. And
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because the number of dissolved particles in a solution is what determines how low the freezing point of a solution can get,
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salts like calcium chloride can do the same job as sodium chloride while using less raw salt to do it.
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Some states like Connecticut have used magnesium chloride salts for de -icing, citing the lower cost of the solution.
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However, there is a downside.
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They're still somewhat corrosive to cars, making them less than ideal.
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And these salts are also bad for the environment when they accumulate.
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It just doesn't happen as fast as with sodium chloride, because less is needed to do the job.
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Figuring out which ions react with what can be a major chemistry puzzle.
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And you can find more of those at Brilliant, the online learning platform with thousands of lessons in science,
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computer science, and math, and the sponsor for this video.
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Their Chemistry and Biology Puzzles course takes interactive learning to the next level, with 28 quick lessons full of puzzles that keep you engaged.
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Some of those puzzles cover the basics of chemical reactions
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that can help you follow along with all of the ions I just rattled off,
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while others pose environmental questions for things like finding a cleaner burning fuel.
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You can try them all for free for 30 days at brilliant .org slash scishow, or by clicking the link in the description down below.
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That link also gives you 20 % off an annual premium Brilliant subscription.
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So, if your ears perked up at the mere mention of the environment, just wait until you hear about this next de -icing alternative.
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Of course, there are other options beyond salts for de -icing roads.
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Some state road agencies have tested all kinds of weird stuff.
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– cheese brine, pickle juice, beet juice, and… pig pee, to name a few?
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Welcome to the wild world of potentially eco -friendly methods for melting road ice.
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Byproducts from vodka distilleries or sugar beet processing facilities contain a lot of sugars, which, when added to road salts,
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helps lower the melting point of the ice, meaning the salt will work better at even lower temperatures.
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But not all eco -options are created equal.
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For instance, some communities have complained about the smell from that beet wastewater,
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water, and some research shows that distillery byproducts can also cause some of those ecosystem problems that we're trying to avoid.
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Urea is also marketed as an eco -friendly solution to road salt,
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since it's also water -soluble and makes a solution with a lower freezing point than pure water.
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And while urea is great at de -icing and is generally safe for pets and children to be around, there are some downsides.
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It doesn't perform well below negative 4 degrees Celsius, and once it gets into a waterway, it decreases dissolved oxygen and causes algal blooms.
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Plus, urea is actually somewhat expensive, at least compared to the other options out there.
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Still, there's definitely a market for more of these less harmful options for de -icing.
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The other way to help de -ice our roads is also the way to make pickles.
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Brine.
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But I'm not talking about your leftover pickle juice.
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Brine is just water that's got a lot of salts dissolved in it.
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And using brine on the roads is a pretty neat way to prevent the ice from forming in the first place.
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When you de -ice a road that's already been snowed upon,
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transportation agencies use wet rock salt to break the bond between the ice and the road, making it safer to drive.
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But the idea behind the brine is to apply liquid salt to the road ahead of time.
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Some places have started brining the roads with liquid salt solution before the snow or ice shows up.
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This limits the amount of ice that can form on the road to begin with, and uses about a quarter of the salt of de -icing.
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Brining requires a lot of infrastructure and planning.
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A community needs trucks with big tanks and pumps to spray the brine onto the pavement's surface.
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This stuff can be expensive.
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However, communities that have invested in brining roads have reported reducing the overall cost of maintaining winter roads,
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even after accounting for the extra equipment and staffing.
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And the reason for the savings is simple, they're just not buying as much salt.
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So, while nothing is perfect, there are absolutely some ways we can move ahead on making our roads safer and more eco -friendly.
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Let's just hope they don't all smell like pig pee.
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Thanks for watching.
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Vocabulaire et conseils d’expression pour cette leçon
Cette leçon d’expression orale s’appuie sur la vidéo « How To Clear Icy Roads, With Science ». Les mots qui reviennent le plus souvent : salt, road, chloride, solution, ice. Cette vidéo contient 60 phrases et 1197 mots à répéter en shadowing. La partie parlée dure 6:02. Le locuteur parle vite, environ 198 mots par minute : attendez-vous à des liaisons et à des sons réduits. Seuls 78 % des mots font partie des 3 000 mots les plus courants en anglais, le vocabulaire est donc exigeant.
Vocabulaire clé de cette vidéo
15 mots de la vidéo à retenir, avec leur prononciation et leur sens :
| Mot | Prononciation | Sens |
|---|---|---|
| freeze verbe | /ˈfɹiːz/ | geler, glacer |
| sodium nom | /ˈsəʊ.di.əm/ | sodium |
| ion nom | /ˈaɪ.ɑn/ | ion |
| puzzle nom | /ˈpʌzəl/ | énigme, mystère |
| infrastructure nom | /ˈɪnfɹəˌstɹʌkt͡ʃə/ | infrastructure |
| juice nom | /d͡ʒuːs/ | jus |
| chemistry nom | /ˈkɛm.ɪ.stɹi/ | chimie |
| melt verbe | /mɛlt/ | fondre, se dissoudre |
| calcium nom | /ˈkælsi.əm/ | calcium |
| salty adjectif | /ˈsɔlti/ | salé |
| lesson nom | /ˈlɛs.ən/ | leçon |
| liquid nom | /ˈlɪk.wɪd/ | liquide |
| wildlife nom | /ˈwaɪldlaɪf/ | faune, nature |
| ecosystem nom | /ˈikoʊˌsɪstəm/ | écosystème |
| technique nom | /tɛkˈniːk/ | technique |
Les verbes à particule que vous entendrez
| Mot | Sens |
|---|---|
| figure out verbe | cerner |
| show up verbe | apparaître, se montrer se pointer |
La grammaire de cette vidéo
Les structures que le locuteur utilise le plus, avec les mots exacts de la vidéo :
| Structure | Dans la vidéo |
|---|---|
| Present perfect have/has + participe passé — une action passée qui compte encore maintenant | have used · have tested · have complained |
| Voix passive be + participe passé — l’accent est mis sur ce qui arrive, pas sur qui le fait | is dissolved · is required · is needed |
Prononciation à surveiller
Le locuteur utilise 9 contractions et formes réduites, comme they're, doesn't, don't. Prononcez-les sous leur forme courte, telles que vous les entendez.
- Les sons « sh » et « zh »: essentially /ɪˈsɛnʃəli/, potentially /pəˈtɛnʃ(ə)li/, concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, subscription /səbˈskɹɪpʃən/, freshwater /ˈfɹɛʃˌwɔːtə(ɹ)/
- Mots longs — placez bien l’accent: infrastructure /ˈɪnfɹəˌstɹʌkt͡ʃə/, ecosystem /ˈikoʊˌsɪstəm/, essentially /ɪˈsɛnʃəli/, potentially /pəˈtɛnʃ(ə)li/, experiment /ɪkˈspɛɹ.ə.mənt/
Les sons difficiles pour les francophones :
- /h/ — il se souffle, il n’est pas muet: harmful /ˈhɑɹmfl̩/, havoc /ˈhævək/, halite /ˈhæl.aɪt/
- /tʃ/ et /dʒ/ — à ne pas adoucir en « ch » et « j »: infrastructure /ˈɪnfɹəˌstɹʌkt͡ʃə/, juice /d͡ʒuːs/, engage /ɪnˈɡeɪd͡ʒ/, oxygen /ˈɑksɪd͡ʒən/, chilly /ˈt͡ʃɪli/
- /r/ anglais — langue recourbée, sans frotter la gorge: freeze /ˈfɹiːz/, infrastructure /ˈɪnfɹəˌstɹʌkt͡ʃə/, chemistry /ˈkɛm.ɪ.stɹi/, crystal /ˈkɹɪstəl/, experiment /ɪkˈspɛɹ.ə.mənt/
Comment s’entraîner avec cette vidéo
- Écoutez la vidéo en entier une fois sans parler et notez les mots que vous ne connaissez pas.
- Commencez à la vitesse 0,75×, répétez phrase par phrase, puis revenez à la vitesse normale quand cela devient facile.
- Enregistrez-vous et comparez avec l’original, en faisant attention à des mots comme freeze, sodium, ion.
Qu'est-ce que la technique du Shadowing ?
Le Shadowing est une technique d'apprentissage des langues fondée sur la science, développée à l'origine pour la formation des interprètes professionnels. Le principe est simple mais puissant : vous écoutez de l'anglais natif et le répétez immédiatement à voix haute — comme une ombre suivant le locuteur avec un décalage de 1 à 2 secondes. Les recherches montrent une amélioration significative de la précision de la prononciation, de l'intonation, du rythme, des liaisons, de la compréhension orale et de la fluidité.