i have a question which you will surely be reluntant to answer, since it is basicly what any book that explains angular momentum tries to examine, through several equations such as torque, and i could just check one of those books and i'd have my answer but, believe me, i have read them. so, i wanted to know about the conservation of angular momentum. the law says that m(rxv) is constant unless axr is not zero. this means that if a particle is moving with radius R and changes to a smaller radius r the velocity will increase by the same factor thus requiring energy input (a normal force). i wanted to know the explanation to this. i know torque is the variation of those quantities and that without torque they should remain the same but i just don't see the relation between radius and velocity. why does velocity increase? i won't probably get much of an answer but if you have read so far, thanks :P.