Newton’s First and Second Laws of Motion are universal: they tell us how any set of forces will affect any object.
If the forces are ‘balanced’ (dread word! — saying ‘total force is zero’ is better, I think) then the object will not accelerate: that is the essence of the First Law. If the sum of the forces is anything other than zero, then the object will accelerate; and what is more, it will accelerate at a rate that is directly proportional to the total force and inversely proportional to the mass of the object; and let’s not forget that it will also accelerate in the direction in which the total force acts. Acceleration is, after all, a vector quantity.
So far, so good. But what about the Third Law? It goes without saying, I hope, that Newton’s Third Law is…
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