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Explain in your own word, why Newton's 3rd Law is possible to observe acceleration of objects.?
Give an example which demonstrate this.
1 Answer
- oldprofLv 77 years ago
Re Newt, SUM(f) = 0, which says for every action there is a reaction force, and they all balance out given a net zero. But we know that A = f/M = 0/M = 0; so how can there possibly be zero or balance forces when there are things accelerating?
Easy. Look here. SUM(f) = 0 = P - F - MA; where P are all the propelling or acting forces, F are all the braking or reacting forces, and MA is the force due to acceleration. Yep. f = MA is one of the forces when we balance out all the forces acting on a body M.
EX: A rocket with total mass M lifting off the pad with thrust P and weight F = W = Mg. So SUM(f) = 0 = P - Mg - MA and A = (P - Mg)/M is the initial acceleration off that pad.
