Hacker News new | comments | show | ask | jobs | submit login

You used 5m instead of 5mm, putting you out by a factor of 1000:

    2 * Pi * 0.005m * 125000/60 s^-1 = 65.4m/s = 235km/h.



Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | DMCA | Apply to YC | Contact

Search: