this post was submitted on 01 Oct 2026
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xkcd #3305: Ground Effect

Title text:

Runners looking for aerodynamic advantage typically wear sneakers because some fancy dress shoes can create wingtip vortices.

Transcript:

Transcript will show once it’s been added to explainxkcd.com

Source: https://xkcd.com/3305/

explainxkcd for #3305

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[–] Azzu@leminal.space 30 points 2 weeks ago (3 children)

An aviation joke? I can't imagine many people getting this without explainxkcd :D

[–] anton@lemmy.blahaj.zone 32 points 2 weeks ago (1 children)

To be fair, you have to have a very high IQ to understand xkcd. The humour is extremely subtle, and without a solid grasp of theoretical physics most of the jokes will go over a typical viewer's head. There's also blackhats nihilistic outlook, which is deftly woven into his characterisation- his personal philosophy draws heavily from early internet forums, for instance. The fans understand this stuff; they have the intellectual capacity to truly appreciate the depths of these jokes, to realise that they're not just funny- they say something deep about LIFE.

[–] boonhet@lemmy.zip 12 points 2 weeks ago
[–] Starfighter@discuss.tchncs.de 26 points 2 weeks ago

Aeronautics isn't too far fetched for a comic series aimed at (astro-)physicists and computer scientists.

[–] Erusset@slrpnk.net 13 points 2 weeks ago

It's hard to run if you aren't touching the ground

[–] explodicle@sh.itjust.works 5 points 2 weeks ago (4 children)

On which body in the solar system could humans run the fastest? I'd imagine low gravity and less atmosphere would help, but if you ran faster than escape velocity you'd fly off an asteroid.

[–] youCanCallMeDragon@lemmy.world 11 points 2 weeks ago (1 children)

Earth. Humans usually die on the other ones.

[–] lugal@sopuli.xyz 5 points 1 week ago (1 children)

On the contrary. Earth is the only planet anyone ever died on.

Well you got me there

[–] AFKBRBChocolate@lemmy.ca 4 points 2 weeks ago

Probably a good physics question, but might have to define "running" more than we generally do. I'd imagine that with super low gravity and minimal atmosphere, the fastest thing would be to have cleats on the toes of your shoes and essentially jump with a shallow angle to the ground and basically fly until you sink enough to do it again.

[–] Dalvoron@lemmy.zip 4 points 2 weeks ago

I think there are benefits and drawbacks to different gravity to earth. As you say, less atmosphere would help with air resistance, but they'd be in contact with the ground less often too and therefore have less opportunity to give themself forward momentum.

We also have to think about breathability of the atmosphere. If they need to wear some gear in order to breathe, that will slow them down

On balance, I think the boring answer of earth seems like the correct one

[–] anton@lemmy.blahaj.zone 3 points 2 weeks ago

Top performing sprinters accelerate faster that 1g, so slightly increasing the gravity would probably make them faster on very short distances.
For long distances it would probably be some low gravity jumping limited by the relative speed between foot and torso that you can create before touching the ground and decelerate before overextending the leg.