This content originally appeared on DEV Community and was authored by Nguyen Khanh Tung
Author: Nguyễn Khánh Tùng
ORCID: 0009-0002-9877-4137
Website: https://traiphieu.com
Abstract
Every fundamental law of physics comes with a quantity and its unit:
- Newton for force,
- Pascal for pressure,
- Joule for energy.
The NKTg Law (Law of Varying Inertia) introduces a new physical quantity — varying inertia — which reflects the combined effect of position, velocity, and mass.
To measure this, I propose the NKTm unit, verified using NASA JPL Horizons data (Neptune, 2023–2024).
Theoretical Basis
The NKTg Law defines motion as:
math
NKTg = f(x, v, m)
where
x: position [L]
v: velocity [L/T]
m: mass [M]
p = m·v: momentum [M·L/T]
Two main forms:
NKTg₁ = x · p (Position–Momentum interaction)
NKTg₂ = (dm/dt) · p (Mass-variation–Momentum interaction)
Both share the same unit: NKTm.
📐 Dimensional Analysis
From NKTg₁: [M·L²/T]
From NKTg₂: [M²·L/T²]
Comparison with classical units:
Quantity Unit Dimension
Force Newton [M·L/T²]
Energy Joule [M·L²/T²]
Power Watt [M·L²/T³]
NKTm₁ NKTm [M·L²/T]
NKTm₂ NKTm [M²·L/T²]
🛰 Verification with NASA Data (Neptune 2023–2024)
Position (x): 4.498e9 km
Velocity (v): 5.43 km/s
Mass (m): 1.0243e26 kg
Momentum (p = m·v): 5.564e26 kg·m/s
Results:
NKTg₁ = x·p ≈ 2.503 × 10³⁶ NKTm
NKTg₂ ≈ -1.113 × 10²² NKTm (assuming micro gas escape)
Total NKTg ≈ 2.501 × 10³⁶ NKTm
🔧 Applications
Astronomy: planetary mass variation, stellar evolution, orbital stability.
Aerospace: rocket trajectory optimization, ion/plasma engines, mass leakage effects.
Earth Sciences: climate modeling, ice melting, sea-level rise, mass redistribution.
Engineering: robotics with variable load, cargo systems, nonlinear vibrations, nanomaterials.
🎯 Why NKTm Matters
A new fundamental measurement unit, independent of Newton or Joule.
Provides a framework for systems with variable mass — beyond Newtonian mechanics or relativity corrections.
Opens new perspectives in cosmology (dark matter, dark energy) and advanced mechanics.
💬 Closing Note
This article aims to clarify the measurement unit of the NKTg Law and show its wide applications — from planetary motion to engineering systems.
My hope is that the developer & science community can see not only the formulas, but also the physical meaning behind them.
🙏 What do you think about introducing a new physical unit like NKTm? Could it be useful for future physics simulations or space exploration models?
This content originally appeared on DEV Community and was authored by Nguyen Khanh Tung