Force and Interactions
Force is the agent of change in Newtonian Mechanics. Without force, everything continues to move with constant velocity, passing through other objects due to the lack of contact forces. When there is change, describing the situation clearly demands noting what kind of forces are acting. This is especially important as it gives clues about which category of models is appropriate:
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It is also important to note whether the force acts over a time interval, in which case it imparts momentum or whether it acts through a distance, in which case it does work.
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