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Physics/What is the best version of newtons' laws of motion?

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Question
1)If there is no (net force or unbalanced force?) on an object,then its velocity is constant.The object is either( at rest or in uniform motion) (velocity=0),or it moves with a constant speed in a (single direction or straight line motion?)

2)The acceleration of a body is directly parallel and poportional to the net force acting on the body,is in the direction of the net force,and is inversely poportional to the mass m of the body.

3)For every action,there is a reaction force with same magnitude and opposite direction

Answer
Actually, I suspect that this as much opinion as anything else. I would say:
1) In the absence of any unbalanced, external force the velocity of an object remains constant.
2) if there is an unbalanced, external force on an object, the object will accelerate in direct proportion to that external force, in the same direction as the force and in inverse proportion to object's mass.
3) For every action force there will always be an equal, but opposite, reaction force.
But language being what it is, each individual might find a slightly different wording to be more explanatory.

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James J. Kovalcin

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I am teaching or have taught AP physics B and C [calculus based mechanics & electricity and magnetism] as well as Lab Physics for college bound students. I have a BS in Physics from the University of Pittsburgh and a Master of Arts in Teaching from same. I have been teaching physics for 34 years. I am constantly updating my skills and have a particular interest in modern physics topics.

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