ABSTRACT
These laws are usually called Newton's laws of motion, even though, as discussed at length in Chapter 5, Newton did not give the second of them in this form. They will be regarded as fundamental postulates, derived from experience, although they may be regarded from other standpoints, e.g. law (2) may be regarded as a relative definition of force or mass. These laws are by no means the only fundamental set of postulates, of course, and indeed, in classical mechanics, a more satisfactory set may be formed from Galileo's principle of relativity and Hamilton's principle of least action, as demonstrated by Landau and Lifshitz (1960). However, Newton's laws, as expressed above, are by far the most familiar, and this justifies the present choice.
