1. The problem statement, all variables and given/known data To simulate gravity a circular space station with a radius of 150m is rotated so that astronauts on the inner surface move at 30m/s. If a 75kg astronaut stands in a bathroom scale, what reading will it give? In newtons. 2. Relevant equations Fc = mv2/r 3. The attempt at a solution Fc = Fg Fg = mv2/r Fg = (75)(900)/150 Fg = 450 N Therefore the scale will say 450 N. I dont get it... 30m/s is 1 sig dig. So my answer should be 400 N? Can somebody confirm this? It just seems weird to write "Therefore the scale will say 400 N" when in reality it will be 50 N greater, which is a big difference. I have to submit my answers for marking and I dont want to lose marks. So are you supposed to use sig digs even if it changes your answer a lot? Because there have been a few instances where I come across questions that should have 1 significant digit in the final answer but that would change my calculated answer by a lot.