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How do Maglev trains work? - Ning Zhao

AdvancedAmerican accentAnimated lesson6 min

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Transcript: 44 sentences

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  1. 0:07 To coincide with the 1964 Tokyo Olympics, Japan launched the world’s first high-speed train, the Shinkansen.
  2. 0:17 Capable of running at 210 kph, this groundbreaking bullet train inspired countries around the world to invest in high-speed rail.
  3. 0:29 Today, these trains regularly travel at over 300 kph, on par with the takeoff speed of a commercial airplane.
  4. 0:40 But could these trains go even faster, whisking passengers to their destinations quicker than the smoothest flight?
  5. 0:48 To answer this, it helps to understand how these trains reach their already impressive speeds.
  6. 0:55 There are three main factors that separate bullet trains from traditional, low-speed trains: engines, aerodynamics, and infrastructure.
  7. 1:09 Most traditional trains are powered by combustion engines, which combust fuel - typically diesel - to turn an electric generator.
  8. 1:20 This electricity is then used to power motors that turn the train’s wheels.
  9. 1:25 High-speed trains, on the other hand, use electric engines to power their motors.
  10. 1:31 This process is more energy efficient than combustion and allows train operators to reach top speeds more quickly.
  11. 1:41 Next up is aerodynamics.
  12. 1:43 While low- and high-speed trains use the same steel wheels to minimize friction with the track, bullet trains are also designed with aerodynamic bodies
  13. 1:55 that slice through air with minimal resistance.
  14. 1:58 Engineers could use these slicker designs on traditional train cars.
  15. 2:03 But while upgrading to electric engines would make low-speed trains more efficient, they wouldn't get much benefit from these aerodynamic designs
  16. 2:13 because of the third factor: infrastructure.
  17. 2:17 Traditional train tracks were built to meet people where they lived, ensuring stations were accessible to any potential passengers.
  18. 2:26 But to prevent derailments in these highly populated areas, trains need to frequently decelerate to safely hit turns and cross roads.
  19. 2:36 High-speed rails, on the other hand, were built to prioritize speed.
  20. 2:41 They run on long, straight lines that avoid road crossings, sharp curves, and high traffic areas.
  21. 2:49 These three differences allow high-speed trains to reach top speeds over double their traditional counterparts.
  22. 2:58 And since their infrastructure allows them to travel longer distances between stops, they spend more time cruising near top speed,
  23. 3:07 often traveling up to three times the average speed of traditional trains.
  24. 3:13 But new technology is emerging to make even faster trains.
  25. 3:19 To eliminate friction between rails and wheels, engineers have developed new magnetic levitation, or maglev, trains.
  26. 3:28 There are two major approaches here.
  27. 3:31 In electromagnetic suspension, magnetized arms wrap under the track and pull the train up.
  28. 3:39 Meanwhile, in electrodynamic suspension, coils embedded in the track create a pattern of alternating magnetic fields that interact with magnets on the train
  29. 3:50 to float the vehicle a few centimeters in the air.
  30. 3:55 To change speed, train operators alternate the direction of the trains’ magnetic field, attracting the front of the train to the next coil to speed up
  31. 4:05 or reversing the field’s phase to brake.
  32. 4:09 Given enough runway, these trains can reach speeds from 430 to a theoretical 600 kph,
  33. 4:18 allowing them to make the over 4,400 kilometer trip from New York City to Los Angeles in as little as seven hours.
  34. 4:28 So why haven’t we built maglev trains, or even high-speed trains, everywhere?
  35. 4:35 First, these trains require lots of energy, most of which is needed to overcome air resistance.
  36. 4:43 In fact, at 300 kph, this task accounts for over 80% of a train’s energy consumption.
  37. 4:52 Engineers are researching ways to reduce air resistance, such as putting maglevs in near-vacuum environments.
  38. 5:00 But building a vacuum-sealed tunnel across an entire country would be an infrastructure project of science fictional proportions.
  39. 5:11 Besides, it’s hard enough to build regular high-speed rails.
  40. 5:15 To go fast, trains need long, straight tracks with wide curves, which are very difficult to build in mountains, cities, or densely populated areas.
  41. 5:27 Building such routes is costly, politically sensitive, and often physically impossible.
  42. 5:34 Despite these hurdles, Japan and China are expanding their existing high-speed and maglev rails, and several projects currently in development
  43. 5:45 might finally bring high-speed rail to the US.
  44. 5:49 But we’ll need to carefully consider our trains’ top speeds alongside cost, energy use, and safety to keep the future of train travel on the right track.

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