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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[–] ch00f@lemmy.world 19 points 3 days ago (1 children)

The tips of the turbine fan blades are going much faster than the plane itself.

[–] 5715@feddit.org 5 points 2 days ago (2 children)

Do you know any rough numbers?

[–] boring_bohr@feddit.org 11 points 2 days ago

According to this document, the Trent XWB from Rolls Royce has a fan diameter of 3m and a reference rotational speed of 2700 rpm for the low pressure stage, which would result in a blade tip speed of 424.1 m/s or 1526.8 km/h according to this calculator

[–] upbeatdingo@piefed.world 4 points 2 days ago (1 children)

I know that some generator turbines go ~3600 rpm

If my (admittedly super rusty) math is right if we assume a radius of 1 meter which would mean a circumference of ~6.28 meters. In that case the tips of the turbines would be moving:

6.28 * 3600 =22,608 meters per minute.

Please feel free to rip up my math as I’m going on little sleep at the moment.

[–] 5715@feddit.org 3 points 2 days ago (1 children)

Search-fu gives me 377 m/s or 1357 km/h.

[–] upbeatdingo@piefed.world 6 points 2 days ago

Gotcha, so I wasn’t too far off.