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## Newton's 1st Law

Newton's first law applies to an object at rest or else moving at constant velocity. It states simply that there can be no acceleration without forces. More technically:

Although perhaps obvious to us, at the time of its proposal 300 years ago this law was a radical departure from conventional thinking. Consider a book sliding across a table: the book will initially move, but eventually will stop. One might guess then that the natural tendency of objects is to be at rest, and this was the thinking 350 years ago. However, Newton's 1st law would imply that for the book sliding across the table the natural tendency is for it to continue moving, and that one thus must do something extraordinary'' to make it stop. We now view this as correct: the extraordinary'' action being taken to stop the book is the force of friction between the book and the table, and indeed objects with little or no contact friction (such as a hockey puck sliding along the ice) do move essentially unimpeded.

Next: Newton's 2nd Law Up: Newton's Laws Previous: Newton's Laws
modtech@theory.uwinnipeg.ca
1999-09-29