Newton's Second Law and Inertial Frames Of Refence

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SUMMARY

Newton's Second Law (N.S.L) is applicable exclusively in inertial frames of reference, where the net force acting on a body equals the time rate of change of its linear momentum. The mathematical expression for N.S.L is given by the equation ∑ F = dp/dt = d(mv)/dt = (dm/dt)v + m(dv/dt). In the context of arbitrary coordinates, the Einstein Summation Convention is utilized, leading to the reformulated expression ∑ F = [(dm/dt)va + m(dva/dt)]ea + mva(dea/dt). The discussion raises the question of whether N.S.L can be applied in accelerating frames of reference by incorporating the term mva(dea/dt) instead of introducing fictitious forces.

PREREQUISITES
  • Understanding of Newton's Second Law and its mathematical formulation
  • Familiarity with inertial and non-inertial frames of reference
  • Knowledge of the Einstein Summation Convention
  • Basic concepts of linear momentum and force
NEXT STEPS
  • Explore the implications of Newton's Second Law in non-inertial frames of reference
  • Study the role of fictitious forces in accelerating frames
  • Investigate the Einstein Summation Convention in advanced physics contexts
  • Examine examples of rotating and uniformly accelerating systems in classical mechanics
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Physics students, educators, and professionals interested in classical mechanics, particularly those focusing on the applications of Newton's laws in various reference frames.

cwstrick
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I have a question about Newton's Second Law and Inertial Frames of Refrence. It is canon that Newton's Second Law is only applicable in an inertial frame of refrence. Newton's Second Law is the net force acting on a body is equal to the time rate of change of the body's linear momentum. Expressed mathematically N.S.L is

[tex]\sum[/tex] F = dp/dt = d(mv)/dt = (dm/dt)v + m(dv/dt)

Lets define a general velocity vector using arbitrary coordinates.The Einstein Summation Convention is being used. Let v = vaea
then (dv/dt) = (dva/dt)ea + va(dea/dt). Substituting this into the equation above and factoring one can arrive at

[tex]\sum[/tex] F = [(dm/dt)va + m(dva/dt)]ea + mva(dea/dt).

In regular cartesian coordinates, the last term in zero. My question is, can one apply N.S.L. in an accelerating frame of refrence by adding the last term, mva(dea/dt), instead of adding ficticious forces?
 
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That last term probably is the fictitious force. Try it with a standard non-inertial frame like a rotating or uniformly accelerating system and see.
 

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