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Lena@gregtech.eu to Science Memes@mander.xyzEnglish · 4 months ago

Doppler

gregtech.eu

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Doppler

gregtech.eu

Lena@gregtech.eu to Science Memes@mander.xyzEnglish · 4 months ago
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  • Omgboom@lemmy.zip
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    4 months ago

    That car is speeding

    • Evil_incarnate@lemm.ee
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      4 months ago

      They’d only get a light sentence anyway.

      • Aurenkin@sh.itjust.works
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        4 months ago

        Depending on the frequency of the offence

        • 0ops@lemm.ee
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          4 months ago

          Might have community service periodically

    • DogWater@lemmy.world
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      3 months ago

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

  • Troy@lemmy.ca
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    4 months ago

    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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      4 months ago

      OK now how fast did old man’s head move

      • Troy@lemmy.ca
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        4 months ago

        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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          3 months ago

          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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          3 months ago

          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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            3 months ago

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

            • TechieDamien@lemmy.ml
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              3 months ago

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

    • Speiser0@feddit.org
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      4 months ago

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

      • Troy@lemmy.ca
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        4 months ago

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

    • burgersc12@mander.xyz
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      4 months ago

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

    • stebo@lemmy.dbzer0.com
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      27 days ago

      deleted by creator

      • Troy@lemmy.ca
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        4 months ago

        Instructions unclear, car stuck in dick.

    • lefixxx@lemmy.world
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      4 months ago

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

      • roscoe@lemmy.dbzer0.com
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        4 months ago

        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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          4 months ago

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

        • NoSpotOfGround@lemmy.world
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          3 months ago

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

      • Rowan Thorpe@lemmy.ml
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        3 months ago

        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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      3 months ago

      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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    3 months ago

    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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    4 months ago

    One shift
    Two shift
    Red shift
    Blue shift

    • Lena@gregtech.euOP
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      4 months ago

      Blue Shift?

      • danc4498@lemmy.world
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        4 months ago

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

        • DosDude@retrolemmy.com
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          4 months ago

          Half life : alyx is not that old.

          • danc4498@lemmy.world
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            4 months ago

            I’d call that half like with an asterisk.

            • RedditRefugee69@lemmynsfw.com
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              4 months ago

              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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                4 months ago

                Yes

                • RedditRefugee69@lemmynsfw.com
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                  3 months ago

                  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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    4 months ago

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

    • marcos@lemmy.world
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      4 months ago

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

  • Rudee@lemmy.ml
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    4 months ago

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

    • Lena@gregtech.euOP
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      4 months ago

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

  • drthunder@midwest.social
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    4 months ago

  • ☂️-@lemmy.ml
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    3 months ago

    thats one FAST car

    • jol@discuss.tchncs.de
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      3 months ago

      And one fast head turn

    • RizzRustbolt@lemmy.world
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      3 months ago

      Only as it’s moving away.

  • DavidGarcia@feddit.nl
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    4 months ago

    what a beatiful green car

  • Kbobabob@lemmy.world
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    4 months ago

    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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      4 months ago

      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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      4 months ago

      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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    4 months ago

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

  • Speiser0@feddit.org
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    4 months ago

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

    • Hazel『They/Them』@lemmy.blahaj.zone
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      4 months ago

      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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        3 months ago

        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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        3 months ago

        (Relativistic doppler effect)

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

    • WIZARD POPE💫@lemmy.world
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      4 months ago

      How would you rotate it?

      • Speiser0@feddit.org
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        3 months ago

        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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    3 months ago

    eeeeeeeeeeeeeeeeeeeyowwwwwwwwwwww

  • DarkCloud@lemmy.world
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    4 months ago

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

    • DavidGarcia@feddit.nl
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      4 months ago

      what do you mean “also”?

    • CheeseNoodle@lemmy.world
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      4 months ago

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

  • Sprocketfree@sh.itjust.works
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    4 months ago

    YEA! SCIENCE JOKES!

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