grain of sand is what like 100um, arm is about a meter so tan-1 0.0001/1 ~ 0.0001 (lim x->0 tan x = x). 360 deg, 60 min in a degree so that's about 2 arc min. D

grain of sand is what like 100um, arm is about a meter so tan-1 0.0001/1 ~ 0.0001 (lim x->0 tan x = x). 360 deg, 60 min in a degree so that's about 2 arc min. Does that make sense?