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Sep20-11, 04:57 AM
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Quote Quote by Studiot View Post
Newton's third law states that to every action there is always an equal and opposite reaction.
OK. (The terminology of 'action' and 'reaction' is a bit old-fashioned.)
A force applied to a mass with the purpose of accelerating it is referred to as the accelerating force.
An odd term, but OK. Let's call the mass of interest mass A. Note that the force on mass A must be exerted by some other mass or object, which we can call mass B.
Immediately this force is applied, an equal and opposite internal force, known as the inertial force, is produced in the mass and this force makes the mass resist any change of motion.
Sure, if you switch to analyzing things from the non-inertial frame of the accelerating mass there will be an inertial force due to that change of reference frames. It's not a 'real' force and it's certainly not the 'reaction force' to the force on mass A. The Newton's 3rd law reaction to the force on A is a force on B.