Shadowing Practice: How To Clear Icy Roads, With Science - Learn English Speaking with Video
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82 משפטים
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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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אוצר מילים והערות הגייה לשיעור הזה
שיעור הדיבור הזה מבוסס על הסרטון “How To Clear Icy Roads, With Science”. המילים שחוזרות הכי הרבה: salt, road, chloride, solution, ice. בסרטון הזה יש 60 משפטים ו-1197 מילים לתרגול Shadowing. הדיבור נמשך 6:02. הדובר מדבר מהר, כ-198 מילים בדקה, אז צפו לצלילים מחוברים ומקוצרים. רק 78% מהמילים נמצאות בין 3,000 המילים הנפוצות ביותר באנגלית, כך שאוצר המילים מאתגר.
אוצר מילים מרכזי בסרטון הזה
15 מילים מהסרטון שכדאי ללמוד, עם ההגייה והמשמעות שלהן:
| מילה | הגייה | משמעות |
|---|---|---|
| freeze פועל | /ˈfɹiːz/ | קָפָא |
| sodium שם עצם | /ˈsəʊ.di.əm/ | נַתְרָן |
| puzzle שם עצם | /ˈpʌzəl/ | חִידָה |
| infrastructure שם עצם | /ˈɪnfɹəˌstɹʌkt͡ʃə/ | תַּשְׁתִּית |
| juice שם עצם | /d͡ʒuːs/ | מִיץ |
| chemistry שם עצם | /ˈkɛm.ɪ.stɹi/ | כִימְיָה |
| melt פועל | /mɛlt/ | ניתך, נמס |
| calcium שם עצם | /ˈkælsi.əm/ | סידן, קלציום |
| salty שם תואר | /ˈsɔlti/ | מָלוּחַ |
| lesson שם עצם | /ˈlɛs.ən/ | שיעור, שִׁעוּר |
| liquid שם עצם | /ˈlɪk.wɪd/ | נוֹזֵל |
| technique שם עצם | /tɛkˈniːk/ | טֶכְנִיקָה |
| compare פועל | /kəmˈpɛɚ/ | השווה \ הִשְׁוָה |
| pet שם עצם | /pɛt/ | חיית מחמד \ חַיַּת מַחְמָד |
| ear שם עצם | /ˈɪə̯/ | אוזן, אֹזֶן |
Phrasal verbs שתשמעו
| מילה | משמעות |
|---|---|
| figure out פועל | הֵבִין, מצא תשובה |
דקדוק בסרטון הזה
המבנים שהדובר משתמש בהם הכי הרבה, עם המילים המדויקות מהסרטון:
| מבנה | בסרטון |
|---|---|
| הווה מושלם (Present perfect) have/has + past participle — פעולה שקרתה בעבר ועדיין יש לה חשיבות או השפעה עכשיו | have used · have tested · have complained |
| סביל (Passive voice) be + past participle — הדגש הוא על מה שקורה, לא על מי שעושה את הפעולה | is dissolved · is required · is needed |
הגייה ששווה לשים לב אליה
הדובר משתמש ב-9 קיצורים וצורות מקוצרות, כמו they're, doesn't, don't. אמרו אותם בצורה הקצרה, כפי שאתם שומעים אותם.
- הצלילים של “sh” ו-“zh”: essentially /ɪˈsɛnʃəli/, potentially /pəˈtɛnʃ(ə)li/, concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, subscription /səbˈskɹɪpʃən/, freshwater /ˈfɹɛʃˌwɔːtə(ɹ)/
- מילים ארוכות — שימו לב להטעמה: infrastructure /ˈɪnfɹəˌstɹʌkt͡ʃə/, ecosystem /ˈikoʊˌsɪstəm/, essentially /ɪˈsɛnʃəli/, potentially /pəˈtɛnʃ(ə)li/, experiment /ɪkˈspɛɹ.ə.mənt/
צלילים שדוברי עברית מתקשים בהם:
- /w/ — שפתיים מעוגלות, לא /v/: liquid /ˈlɪk.wɪd/, wildlife /ˈwaɪldlaɪf/, freshwater /ˈfɹɛʃˌwɔːtə(ɹ)/, waterway /ˈwɔːtəweɪ/, watery /ˈwɔtəɹi/
- /æ/ — פתוח יותר מה-“אֶ” העברית, לא כמו “a” ב-“cup”: calcium /ˈkælsi.əm/, math /mæθ/, react /ɹiːˈækt/, interactive /ˌɪn.tɚˈæk.tɪv/, atom /ˈætəm/
- /r/ — הלשון לא נוגעת בשום מקום, לא ה-“ר” הגרונית: freeze /ˈfɹiːz/, infrastructure /ˈɪnfɹəˌstɹʌkt͡ʃə/, chemistry /ˈkɛm.ɪ.stɹi/, crystal /ˈkɹɪstəl/, experiment /ɪkˈspɛɹ.ə.mənt/
איך לתרגל עם הסרטון הזה
- הקשיבו לכל הסרטון פעם אחת בלי לדבר, ורשמו את המילים שאתם לא מכירים.
- התחילו במהירות 0.75×, תרגלו Shadowing משפט אחר משפט, וחזרו למהירות רגילה כשזה מרגיש קל.
- הקליטו את עצמכם והשוו למקור, תוך תשומת לב למילים כמו freeze, sodium, puzzle.
מהי טכניקת השאדואינג?
שאדואינג היא טכניקת למידת שפה מבוססת מדע שפותחה במקור להכשרת מתורגמנים מקצועיים ופופולרית על ידי הפוליגלוט ד"ר אלכסנדר ארגואלס. השיטה פשוטה אך עוצמתית: אתה מקשיב לאודיו באנגלית ילידית וחוזר עליו בקול רם מיד — כמו צל העוקב אחרי הדובר עם עיכוב של 1–2 שניות בלבד. בניגוד להאזנה פסיבית או תרגילי דקדוק, שאדואינג מכריח את המוח והשרירים בפה לעבד ולשחזר דפוסי דיבור אמיתיים בו זמנית. מחקרים מראים שזה משפר משמעותית את דיוק ההגייה, האינטונציה, הקצב, הדיבור המחובר, הבנת השמיעה ושטף הדיבור — מה שהופך אותו לאחת השיטות היעילות ביותר להכנה לIELTS Speaking ולתקשורת באנגלית בעולם האמיתי.