Hacker News new | ask | show | jobs
by throwaway4good 700 days ago
Supersonic = +1 mach, hypersonic = +5 mach.
1 comments
dghughes 699 days ago
But toothbrushes are ultrasonic. I can never find mine.
link
banku_brougham 699 days ago
the plasma ball is opaque to radar, making it hard to detect.
link