Newtons laws ASSUME an inertial frame he defined that condition it is covered here ... read it
https://en.wikipedia.org/wiki/Inertial_frame_of_referenceGalileo had everything Relative in his physics
Newton needs to fix everything to a single position he does this
Newton posited an absolute space considered well approximated by a frame of reference stationary relative to the fixed stars. An inertial frame was then one in uniform translation relative to absolute space. However, some scientists (called "relativists" by Mach), even at the time of Newton, felt that absolute space was a defect of the formulation, and should be replaced.
So Newton assumes some star or point or something is not moving and thus he deals with forces coming from movement as fictional.
WHY DID HE DO THIS?
The answer is energy ...
Newton is all about energy what he is trying to do is exchange energy in all references.
The problem he is struggling with is if energy arises in a relative frame (that is locally) how does it relate to something else. Take a spinning weight I allow the energy in the forces to create locally but now I create another spinning weight. When I smash the two into each other how does the energy of one system relate to the other I need some common reference.
So Newton made his first law ... READ IT VERY CAREFULLY.First law: When viewed in an
inertial reference frame, an object either remains at rest or continues to move at a constant velocity, unless acted upon by an external force.
Newton is well aware his laws won't hold in accelerating (non inertial frame) he assumes that an inertial frame must exists and asks you move the calculation to there and bring the acceleration effects in as fictional forces. Don't complain to me about it ... that is what Newton did and so go complain to him. Your teacher at school probably left that bit out. Newton goes into elaborate detail about how to find an inertial frame but no layman ever bothers to read his works.
The bit layman never seem to get
Newtons laws are not valid in accelerating frames they were never intended to be (AKA the 1st law). Newton isn't stupid almost any calculation in an accelerating frame is going to violate them. That is what happened to Bill G and I was curious to see if he knew why. His argument was you simply find a nice inertial frame move all the calculations to there include all the fictional forces and there you have problem solved. The sting in the tail is if there isn't at least one point in space that is stationary you aren't going to be able to use it on calculations on the universe as a whole because you can't satisfy the first law.
What happens in versions of relativity is you are going to link energy using a different reference not universal co-ordinates like Newton did. Most versions of relativity will link it thru Mass ... Einsteins version is E=MC2. That allows you to connect energies in relative frames and explains why the energy in one local system is related to another in always the same way.
There is nothing to really discuss this is all very basic, just layman never seem to get it that Newtons first law restricts where you can use the laws from ... that is it's intention by design.
So are you happy with all that, or do you still want to try and insist you can use Newton laws in an accelerating frame and we throw Newton's first law out?
