Mike from Phoenix wrote in with an observation on how scales work, and how to use this to your advantage.
I noticed at my son’s pinewood derby this morning that his car weighed in at 5.1 ounces (the scale they used read out to one decimal place). I was a bit surprised and did a little bit of sanding – surely not enough to even come close to one tenth of an ounce, I thought. Out of curiousity, I weighed again – this time it came in at 5.0 That got me to wondering if the scale actually rounded to the nearest decimal place. Perhaps he really came in at first at just a hair over 5.05 … then my sanding perhaps got him just a hair under 5.05 ounces and then the scale at that point rounded down to 5.0 ….so, it occurred to me that if my theory is right then it’s sort of a way to add an extra 1/20th of an ounce to one’s car and still be “legal” (and thus maximize the potential energy)
Great thought, Mike. Only quibble I have is that I’d love to see your son doing the sanding and getting the car ready on race day. It is his car, after all.