This manuscript presents a comprehensive mechanical derivation of the speed of light ($c$) as an emergent property of spacetime under gravitational potential, using the Z.I.P.P.E.D. (Zwanenburg Interaction of Potential and Pressure-Emergent Dynamics) framework. By introducing two fundamental parameters—the Zwanenburg-graad ($Z_g = 1.585018443$), representing spacetime’s elastic resistance, and the Delta Zwanenburg ($\Delta = 3.577919735891648 \times 10^{-17},\text{m}$), representing the finite mechanical tolerance of the substrate—the study demonstrates that $c$ is not an absolute constant but a causal equilibration speed of the mechanical medium. Numerical predictions are provided for Earth, Mars, and the Moon, explaining observational phenomena such as Shapiro-delay, Pioneer-anomalies, and the trajectory of Oumuamua as direct consequences of the Delta Zwanenburg response. This work shifts the perspective of fundamental physics from abstract geometry to a tangible, mechanically consistent model. Keywords / Hashtags: #VariableSpeedOfLight #ZIPPEDFramework #ZwanenburgGraad #DeltaZwanenburg #EmergentPhysics #GravitationalPotential #ShapiroDelay #PioneerAnomaly #Oumuamua #MechanicalUniverse #TheoreticalPhysics