Equation 5 · Part 6 · From Origins to Frontier: A History of Planetary Science and Exploration
Symbol eta
What this part means
eta occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.
Its job in the formula
eta occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.
Full expression→Symbol eta→Article meaning
The passage around this formula
…over geological time. The basic settling physics is captured by a Stokes-law sinking velocity for a dense blob of radius r and density moving through a less dense, viscous mantle of density and viscosity : . This is a first-order model, not a complete theory of core formation — real planetary interiors involve diapirism, iron rain, and turbulent entrainment rather than single isolated blobs — but it exposes the essential dependency: differentiation requires a large enough…
Learn the underlying idea
A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.
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