Conservation of Momentum
In the corollaries that immediately follow, Newton explains how his laws of motion provide a method for solving various problems of mechanics—even complex ones involving multiple forces or multiple interacting bodies. Newton’s wheel, for example, illustrates what happens when multiple torques act on a rotatable body. In this example, the torques which act to rotate the wheel are caused by forces which are not directed perpendicularly to the lever arm. How does Newton deal with this added complication? Following Newton’s wheel example are three very important corollaries. They introduce what is now known as the principle of conservation of momentum. What does this principle state? Is it an independent principle, or does it follow from Newton’s axioms alone.