this post was submitted on 20 Jan 2026
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I was watching a SciFi tv show where large objects had an outer speed limit of 18000 kph and that got me wondering what things in everyday life are faster than even 500 kph.

I know bullets can be fast, but they are not exactly everyday life (at least in my life).

I included mass for obvious relativistic reasons.

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[–] kreskin@lemmy.world 2 points 19 hours ago* (last edited 19 hours ago)

radio waves dont have mass but do have relativistic mass. And you didnt clarify whether relativistic mass counted, so I'm going to go with radio waves. They travel at the speed of light. I am the winner. I'd like my nobel prize in literature now.

[–] diabetic_porcupine@lemmy.world 3 points 23 hours ago

There’s a dirty joke in here somewhere

[–] Etterra@discuss.online 6 points 1 day ago (1 children)

All every day objects but photons have mass. Maybe also neutrinos.

[–] 5715@feddit.org 1 points 1 day ago (1 children)
[–] Etterra@discuss.online 2 points 7 hours ago

While faith also has no mass, that's because it's an abstract concept, not an object.

[–] YiddishMcSquidish@lemmy.today 11 points 1 day ago

Neutrinos. About 100 trillion go through you every second with about .000001 percent interacting with you. And they have a non zero mass.

[–] SirSamuel@lemmy.world 70 points 2 days ago (1 children)

The shortest unit of time in the multiverse is the New York Second, defined as the period of time between the traffic lights turning green and the cab behind you honking.

  • Terry Pratchett, Lords and Ladies
[–] jim3692@discuss.online 2 points 14 hours ago (1 children)

Let's break it down...

The distance, between the traffic light and the cab driver, should be approximately 10 meters.

The time light needs to reach the cab driver's eyes is:

D ÷ c = 10 ÷ 299,792,458 = 0.0000000333... seconds = 0.0000333... milliseconds

The distance between the cab's horn and your ears, should be approximately 5 meters.

The time needed for the cab's honk sound, to reach our ears is:

D ÷ u = 5 ÷ 295 = 0.0169491525 seconds = 16.9491525 milliseconds

If the cab driver had a reaction time of zero, it would still take 16 milliseconds for us, to hear their honk.

The conclusion is that cab drivers have a negative reaction time, so that they can honk before the light turns green, breaking causality.

[–] Rai@lemmy.dbzer0.com 3 points 1 day ago

Me, at the end of any social engagement.

It’s like that episode of Simpsons where they’re filming something at the Simpsons’ house and Homer learns there’s snacks. He suddenly becomes a Homer-shaped cloud of dust.

[–] ch00f@lemmy.world 54 points 2 days ago (4 children)

The crack of a whip is a sonic boom caused by the tip going supersonic.

[–] emotional_soup_88@programming.dev 17 points 2 days ago (2 children)

Some sex includes supersonic elements, then.

[–] fartographer@lemmy.world 12 points 2 days ago (1 children)

Traditionally, you use a rider's crop in sex, in which case, the cracking sound is the flap clap when you slap.

Bull whips, the ones that go supersonic, are often considered less sexy because they rip flesh and make people stop feeling all good and sexy.

Not that I've ever used either in sex. This is just what was explained to me back when I did photo shoots for BDSM community members and events.

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[–] FooBarrington@lemmy.world 16 points 2 days ago (3 children)

🎵 I wanna make a supersonic man out of you 🎶

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[–] HobbitFoot@thelemmy.club 29 points 2 days ago (3 children)
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[–] ch00f@lemmy.world 41 points 2 days ago* (last edited 2 days ago) (7 children)

Glass cracks propagate at an absurdly fast rate. Something like 4x the speed of sound (1400m/s). Not a physical thing moving, but very common.

[–] Willy@sh.itjust.works 17 points 2 days ago (1 children)

I think it would propagate at the speed of sound in glass.

[–] gloktawasright@lemmy.world 10 points 2 days ago* (last edited 2 days ago)

It seems that depending on the type of glass and the direction of the waves (longitudinal, shear, or Extensional) the speed of sound in glass can be between 2300-6000 m/s

Longitudinal is the type we normally think of though, and that is between 3900-5600 m/s. Which is still much more variation than I was expecting.

The speed of sound in air is around 340 m/s depending on temperature.

So if the op is correct about the speed, then it seems the cracks propagate slower than the speed of sound in glass.

https://www.engineeringtoolbox.com/sound-speed-solids-d_713.html

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[–] exasperation@lemmy.dbzer0.com 5 points 1 day ago (1 children)

The crack of a bullwhip is caused by the tip exceeding the speed of sound, around 750 mph/1250 kph.

[–] Tar_alcaran@sh.itjust.works 5 points 1 day ago (1 children)

How many bullwhips are cracking your general area on an average day?

[–] MidsizedSedan@lemmy.world 1 points 19 hours ago

The whip cracking factory. Duh...

[–] stringere@sh.itjust.works 15 points 2 days ago (1 children)

Mantis shrimp punches travel 12 to 23 meters per second (approximately 27 to 51 miles per hour) in water the acceleration involved can reach up to 10,000 Gs.
The peak force generated by a mantis shrimp’s punch can be as high as 1500 Newtons, which is over 2500 times the animal’s own body weight.
The acceleration of their punch is such thay it creates a cavitation bubble which, when it collapses, can generate 8,500 degrees Fahrenheit – nearly as hot as the sun’s surface at 10,000 degrees Fahrenheit.

We named ours Smeagol.

[–] yermaw@sh.itjust.works 8 points 2 days ago

The Mantis Shrimp is one of the few things that make me question pure raw evolution. How the fuck can you just evolve a sci fi plasma pistol?

[–] lgsp@feddit.it 36 points 2 days ago (5 children)

Satellites are visible and move at some km per second. Pretty fast

Inside the atmosphere anything faster than some hundreds km/h get so much drag that they either are extremely small (bullets) or extremely powerful (planes, maglev trains)

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[–] ch00f@lemmy.world 29 points 2 days ago (12 children)

The air leaving your lungs during a sneeze is moving roughly 100mph.

[–] gothic_lemons@lemmy.world 2 points 22 hours ago

I sneeze obnoxiously loud. I bet I break 130 mph easy. How do I go about testing this?

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[–] LaLuzDelSol@lemmy.world 8 points 2 days ago (1 children)

Hmm how about CRT monitors/televisions? Not that common these days but they are basically little particle accelerators that shoot electrons at a pretty good fraction of the speed of light (like 30%). But I guess that's not really an answer to you question unless you define electrons as objects. I guess my other answer would be airbags which deploy at about 300 kmph

[–] Tar_alcaran@sh.itjust.works 2 points 1 day ago

unless you define electrons as objects.

Well, only sometimes.

[–] MalReynolds@slrpnk.net 17 points 2 days ago (8 children)
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[–] bjoern_tantau@swg-empire.de 17 points 2 days ago (3 children)

Depends on how you define everyday life, but there are currently trillions of Neutrinos flying through you at almost light speed. I think their mass still hasn't been measured. But it's pretty low.

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