Unified Perspective on Kinetic Energy | Mass Concepts in Classical, Relativistic, and Extended Classical Mechanics
Kinetic Energy and Effective Mass | Energy and Effective Mass | Phase Shift and Time Distortion | Sign of mᵉᶠᶠ in Classical Mechanics | Hooke's Law over Length Contraction | Force, Deformation, and Time Distortion


Energy and Effective Mass in Motion

 

In classical mechanics, the total energy (E) of a system is defined as:

 

E = PE + KE

 

Potential Energy When v = 0:

 

When an object is at rest, all of its energy is stored as potential energy:

 

Eₜₒₜₐₗ = PE

 

which means the total mass equivalent remains simply m.

 

Energy Distribution When v > 0:

 

Once an object gains velocity, part of its potential energy is converted into kinetic energy:

 

PE − ΔPE = PE + KE

 

The change in potential energy (ΔPE) appears as kinetic energy:

 

KE = −ΔPE

 

Effective Mass Contribution:

 

Since kinetic energy arises from potential energy loss, the effective mass associated with kinetic energy follows:

 

|mᵉᶠᶠ| = −ΔPE

 

This ensures that total energy remains balanced, with kinetic energy representing a redistributed form of the system’s original mass-energy.

 

Given that potential energy (PE) corresponds to the inertial mass (m), and kinetic energy (KE) is linked to an effective mass (|mᵉᶠᶠ|), we express the force equation as:

 

F = |mᵉᶠᶠ|a

 

where the effective mass accounts for both the deformation-induced contribution from stiffness (k) and the inertial mass (m):

 

|mᵉᶠᶠ| = |kΔL|/a

 

Substituting this into the force equation:

 

F = (|kΔL|/a)a

 

Expanding into the energy relation:

 

E = PE + KE m + |mᵉᶠᶠ|

 

Since mᵉᶠᶠ contributes to balancing total energy, the correct formulation becomes:

 

E = m + |kΔL|/a

 

where kinetic energy is directly linked to effective mass (|mᵉᶠᶠ|), sometimes misinterpreted as relativistic mass (m′) and associated with time distortion (Δt′) in certain contexts.