Is Newton's Second Law Valid in an Accelerating Reference Frame?

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SUMMARY

Newton's Second Law, expressed as Fnet=ma, is valid in a lab frame of reference but fails in an accelerating reference frame. When analyzing a frame moving with constant acceleration a1, the acceleration becomes non-invariant, demonstrating that F=ma does not hold. The Galilean transformation shows that while velocities and displacements differ, the relationship between force and mass remains consistent only in inertial frames. This conclusion is critical for understanding the limitations of classical mechanics in non-inertial frames.

PREREQUISITES
  • Understanding of Newton's Second Law (F=ma)
  • Familiarity with Galilean transformations
  • Knowledge of inertial vs. non-inertial reference frames
  • Concept of invariant mass in physics
NEXT STEPS
  • Study the implications of non-inertial frames in classical mechanics
  • Explore the concept of pseudo-forces in accelerating reference frames
  • Learn about the transition from classical mechanics to relativistic mechanics
  • Investigate the role of acceleration in the context of general relativity
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Students of physics, educators teaching classical mechanics, and anyone interested in the foundational principles of motion and reference frames.

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Homework Statement


In a lab frame of reference, an observer finds Newtons second law is valid in the form of Fnet=ma. Show that Newtons second law is not valid in a reference frame moving past the laboratory frame of problem 1 with a constant acceleration a1. assume that mass is an invariant quantity and is constant in time.


Homework Equations


f=ma


The Attempt at a Solution


i don't get how to show this, i get how to show that the velocities and displacement would be different but not how to relate that to the force
 
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Suppose instead that we wish to show that NSL is valid in a 2nd frame moving at constant speed b. The Galilean (sp?) transformation is

x' = x - bt

where the primed quantities are in the moving frame, and b is some constant speed. If we differentiate this twice with repsect to time, we obtain

a' = a

Since mass is invariant, F = ma holds in both frames.

Now do the same thing, but assume that b = a1 t, also the speed of the moving frame but written in terms of a constant acceleration a1 and time. You should find that acceleration is this case is not invariant.
 

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