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Isaac Newton in Principia Law II says:

"the change of motion is proportional to the motive force impressed, and takes place following the straight line in which that force is impressed". "If some force should generate any motion you please, a double will generate a double....whether it has been impressed all at once, or gradually and successively".

The textbooks often say that "the modern formulation is $F=ma$". But change of motion is $\Delta (mv)$, and the force impressed is over time. Would it be fair to say that what Newton is stating is the modern equation of Impulse, not Force?

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Yes, I think that if the phrase 'motive force' had been removed and a blank space substituted, a present-day physicist would fill in "impulse". On the other hand, Newton might not have objected if someone had suggested that he add the words "and to the length of time for which it acts" after "the change of motion is proportional to the motive force impressed", in which case 'motive force' would mean just that. We shall never know.

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