Can anyone recommend a text book or web paper that proves that, in general, a free rigid body will act in the following way when the body is subjected to a force (or impulse) that is torque producing: a) The center of mass (CM) moves in a straight line. b) The body rotates about an axis through its CM. (By "free" I mean unconstrained.) It seems intuitive and many text books state the above. But the ones I've looked at don't seem to present a proof. Thanks.