I've been following recent threads with interest and amusement. There seems to be a sentiment that we should teach mechanics just as it was stated by Newton. This is as reasonable as applying the writings of learned farmers in the 18th century or nomadic shepherds in 1500 BCE to our present situation. I've read the Principia (in translation, I must admit) and I find the reasoning hard to follow and even harder to teach. Surely we are justified in using more recent developments of these notions, just as we are justified in glossing over the most recent ones, in order to provide students with opportunities to absorb the simple beauty we are teaching.
Flame away.
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