[[Isaac Newton]]'s 3 laws of motion form the basis for [[classical mechanics]]. They are:
[[Isaac Newton]]'s 3 laws of motion form the basis for [[classical mechanics]]. They are:
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1) An object in motion will remain in motion in a straight line unless acted upon by an external force. An object at rest will remain at rest unless acted upon by an external force. (Or, alternatively, an object's velocity remains constant unless the object is acted upon by an external force.)
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#An object in motion will remain in motion in a straight line unless acted upon by an external force. An object at rest will remain at rest unless acted upon by an external force. (Or, alternatively, an object's velocity remains constant unless the object is acted upon by an external force.)
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#The rate of change of an object's [[momentum]] is equal to the net force acting on it (<math> \vec F = d{\vec p}/dt </math>, sometimes written as <math> \vec F = m\ \vec a</math> when mass can be assumed to be constant).
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2) The rate of change of an object's [[momentum]] is equal to the net force acting on it (<math> \vec F = d{\vec p}/dt </math>, sometimes written as <math> \vec F = m\ \vec a</math> when mass can be assumed to be constant).
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#For every action there is an equal and opposite reaction; or, more precisely, the total momentum of any isolated system is always constant.
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3) For every action there is an equal and opposite reaction; or, more precisely, the total momentum of any isolated system is always constant.