Hi all. I'm a game programmer with very little exposure to physics. I had one class in high school that spent 6 weeks "teaching me" what we learned on the first day in calculus class about velocity and acceleration. So please be patient :). For something I'm programming, I'm trying to achieve realistic interactions between rigid bodies. I'm having trouble understanding physics of rotations. If I had a pencil floating in space, outside of gravity, air resistance, etc., and I pushed on the eraser, would the pencil rotate around some point (probably the centroid of mass), or would the whole pencil move forward, just as though I had split the force and pushed on both the eraser and on the pencil lead? All discussions I have found online seem to expect I have a pivot/fulcrum/etc. I have always assumed that in their absence there is no rotation, and that things like lamp posts tipping over when you push the top are because of a pseudo-fulcrum caused at the base by friction. However, the simulation at http://www.myphysicslab.com/collision.html has me worried that I've got this all wrong. Yet if this is so, then why do you need to use both your thumb and your index finger to turn a screw, rather than just pushing on one side? Aside from this particular question, in general does anybody have good advice for a computer programmer / mathematician with no physics training to get up to speed on "everything" there is to know about Newtonian Mechanics? Everything I can find on the internet either seems to be the limited "practical" subset they teach in High School (i.e. all angular momentum discussion seems to suppose a lever arm with some part of the object rigidly anchored), or else so rigorous as to be useless to someone just setting out (notational myopia that, necessary for correctness and the specialist, nonetheless occludes comprehension and overview-understanding). Thanks!