Comment by JoeAltmaier
14 years ago
I had this insight in Junior High - testing friction by putting blocks on top of other blocks, or in a block train, and using a 'force meter' to see how hard I had to pull. The 'force meter' was a piece of spring steel stuck into another block, with a hook on the end.
It was totally non-linear on every surface I tested. The book said it was supposed to be linear. The students were all furtively fudging it, and eventually the teacher said something like "well, its supposed to be linear so do the best you can".
Insight: this was all a bunch of crap. Turns out that friction is totally non-linear anyway, for most materials, but I didn't read that until 20 years later.
That reminds me of a story about Richard Feynman visiting a physics class outside the US. The diplomat types were very upset with him for pointing out that their books and classes were terrible, teaching things like the energy of a ball going down an incline without taking rotational kinetic energy into account.
http://v.cx/2010/04/feynman-brazil-education
Yes, thank you. That's exactly the one I was thinking of.