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Lena@gregtech.eu to Science Memes@mander.xyzEnglish · 6 个月前

Doppler

gregtech.eu

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Doppler

gregtech.eu

Lena@gregtech.eu to Science Memes@mander.xyzEnglish · 6 个月前
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  • Omgboom@lemmy.zip
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    6 个月前

    That car is speeding

    • Evil_incarnate@lemm.ee
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      6 个月前

      They’d only get a light sentence anyway.

      • Aurenkin@sh.itjust.works
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        6 个月前

        Depending on the frequency of the offence

        • 0ops@lemm.ee
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          6 个月前

          Might have community service periodically

    • DogWater@lemmy.world
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      6 个月前

      I bet that guy feels like he gets where he’s going in no time at all!

  • Troy@lemmy.ca
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    6 个月前

    Okay, just back of the envelope math. Assuming the car is truly 550nm, so the blue car is 400nm, and the red car is 700nm… How fast is the car going?

    Napkin math says 0.27c.

    Δλ=λ(V/c)

    Now someone else can figure out the kinetic energy of the car and why the whole continent just exploded…

    • passiveaggressivesonar@lemmy.world
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      6 个月前

      OK now how fast did old man’s head move

      • Troy@lemmy.ca
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        6 个月前

        Okay, napkin math… his nose is about 20cm long, and assuming it rotated about a perfect circle. The car moved say 10m. At the speed the car is moving, it covers that distance in ~120ns. So he has to move the end of his nose around a quarter circle of radius 20cm in 120ns. Let’s say 30cm total movement, for easy math. 0.25cm/ns or 0.00025m/ns. The speed of light is 0.300m/ns, so we’re talking about ~0.001c at the tip of his nose. Which is incidentally very close to the speed of sound in air.

        So, probably not quite a sonic boom off the end of his nose. Assuming my math is correct. Very strong neck muscles. Also, he’s been vapourized.

        • DogWater@lemmy.world
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          6 个月前

          Ah this is so great. In the transonic regime (just below 1.0 Mach) the air moving over the surface of his nose will break the speed of sound as it gets out of the way.

        • TechieDamien@lemmy.ml
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          6 个月前

          I think you missed a factor of 1000 when comparing against the speed of sound in air. I think it should be almost 1000 times the speed of sound, so definitely sonic boom and definitely vaporised!

          • Troy@lemmy.ca
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            6 个月前

            It’s very possible. Napkins are notorious for stealing orders of magnitude.

            • TechieDamien@lemmy.ml
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              6 个月前

              What is a factor of 1000 between friends anyway? (Especially cosmologist friends)

    • Speiser0@feddit.org
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      6 个月前

      Did you take into account that the car is not driving directly towards the viewer?

      • Troy@lemmy.ca
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        6 个月前

        I ain’t doing hyperbolic equations on my napkin ;)

    • burgersc12@mander.xyz
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      6 个月前

      So about 180 million MPH. I hope he doesn’t get a ticket!

    • stebo02@lemmy.dbzer0.com
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      deleted by creator

      • Troy@lemmy.ca
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        6 个月前

        Instructions unclear, car stuck in dick.

    • lefixxx@lemmy.world
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      6 个月前

      Why explode, the car didn’t accelerate or interact with the continent

      • roscoe@lemmy.dbzer0.com
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        6 个月前

        Even ignoring the tires interacting with the road, you have air molecules. I don’t think that would be enough to destroy a continent, but it would be very destructive.

        Here is a cool What If? from xkcd about throwing a baseball at 0.9c.

        • lefixxx@lemmy.world
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          6 个月前

          Sound like a ton worth of mass would do a lot of damage indeed

        • NoSpotOfGround@lemmy.world
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          6 个月前

          Wow, that seems to be the very first What If ever!

      • Rowan Thorpe@lemmy.ml
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        6 个月前

        For the same reason this baseball causes an expanding plasma-ball disintegrating everything. Fusion with air molecules that can’t get out of the way fast enough https://what-if.xkcd.com/1/

    • Venator@lemmy.nz
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      6 个月前

      someone else can figure out the kinetic energy of the car and why the whole continent just exploded…

      It’s not on fire or melting the asphalt beneath it, so it must be really aerodynamic, and have really low rolling resistance tyres…

  • go $fsck yourself@lemmy.world
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    6 个月前

    Here’s the original image. It was originally posted in 2017 and has been shared so many times it was difficult to find a good copy. I had to use wayback to get this copy.

  • Alabaster_Mango@lemmy.ca
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    6 个月前

    One shift
    Two shift
    Red shift
    Blue shift

    • Lena@gregtech.euOP
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      6 个月前

      Blue Shift?

      • danc4498@lemmy.world
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        6 个月前

        Damn, remember when Valve made half life games? It was a better time back then.

        • DosDude@retrolemmy.com
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          6 个月前

          Half life : alyx is not that old.

          • danc4498@lemmy.world
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            6 个月前

            I’d call that half like with an asterisk.

            • RedditRefugee69@lemmynsfw.com
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              6 个月前

              Why?

              Because it’s not as easy to get to where you can play it? People don’t write off new games in a series that require a $1,000 PC upgrade, why is a VR headset you can get for much cheaper any different?

              If it’s not the barrier to entry, is it the format? Is Metroid Prime not still a Metroid game? Is Ocarina of Time not a Zelda game?

              • danc4498@lemmy.world
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                6 个月前

                Yes

                • RedditRefugee69@lemmynsfw.com
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                  6 个月前

                  Well I disagree with you on every point, then:

                  • Ocarina of Time is a Zelda game.

                  • Metroid Prime is a Metroid game.

                  • The Witcher 3 is a Witcher game.

                  Ergo, Half-Life : Alyx is a Half-Life game.

  • Wugmeister@lemmy.dbzer0.com
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    6 个月前

    Pretty sure the sonic boom of this car passing will kill this poor man

    • marcos@lemmy.world
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      6 个月前

      Well, when that finally happens the car will be fine, far away from Earth.

  • Rudee@lemmy.ml
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    6 个月前

    If that guy is keeping track of that car, his neck is def broken

    • Lena@gregtech.euOP
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      6 个月前

      Everything around the car would be broken too, including the car

  • drthunder@midwest.social
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    6 个月前

  • ☂️-@lemmy.ml
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    6 个月前

    deleted by creator

    • jol@discuss.tchncs.de
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      6 个月前

      And one fast head turn

    • RizzRustbolt@lemmy.world
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      6 个月前

      Only as it’s moving away.

  • DavidGarcia@feddit.nl
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    6 个月前

    what a beatiful green car

  • Kbobabob@lemmy.world
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    6 个月前

    For some reason I can never remember which causes red or blue shift, but with this I might actually remember it

    • Lena@gregtech.euOP
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      6 个月前

      Blue has a smaller wavelength, so when something is approaching fast it “squishes” the light, making a smaller wavelength.

    • 0ops@lemm.ee
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      6 个月前

      Maybe it’s slightly convoluted but here’s how I tackle it in my head: I just think of infrared and ultraviolet, ultraviolet being greater frequencies than violet and infrared being the opposite for red. Blue is on the way from infrared to ultraviolet, so blue has a greater frequency than red.

  • OhStopYellingAtMe@lemmy.world
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    6 个月前

    You can either know the position of the car or the momentum, but not both.

  • Speiser0@feddit.org
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    6 个月前

    But why is the car stretched? And why doesn’t it appear rotated?

    • Hazel『They/Them』@lemmy.blahaj.zone
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      6 个月前

      It’s how Doppler works.

      I don’t understand it enough to actually explain but Wiki does a pretty good job.

      • nialv7@lemmy.world
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        6 个月前

        The poster you are replying to is pointing out the inaccuracies that this comic didn’t consider relativistic effects.

      • Speiser0@feddit.org
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        6 个月前

        (Relativistic doppler effect)

        But does it affect the object that is emitting the wave?

    • WIZARD POPE💫@lemmy.world
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      6 个月前

      How would you rotate it?

      • Speiser0@feddit.org
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        6 个月前

        If you look at an object that is moving near the speed of light, it appears rotated, see https://en.wikipedia.org/wiki/Terrell_rotation.

  • Lovable Sidekick@lemmy.world
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    6 个月前

    eeeeeeeeeeeeeeeeeeeyowwwwwwwwwwww

  • DarkCloud@lemmy.world
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    6 个月前

    This is also playing on red-shift/blue-shift.

    • DavidGarcia@feddit.nl
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      6 个月前

      what do you mean “also”?

    • CheeseNoodle@lemmy.world
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      6 个月前

      They are the same effect just using different kinds of wave.

  • Gerprimus@feddit.org
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    6 个月前

    I love it!

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