← All parts of this equation

Equation 5 · Part 1 · From Origins to Frontier: A History of Planetary Science and Exploration

Symbol v

v=2gr2(ρm−ρs)9ηv = \frac{2 g r^2 (\rho_m - \rho_s)}{9\eta}
vv

What this part means

v is part of the quantity the equation computes from the expression on the right.

Its job in the formula

v is part of the quantity the equation computes from the expression on the right.

The passage around this formula

Comparative planetology treats a planet as a layered physical system rather than a point of light, and the physics of that layering is not exotic — it is gravitational settling under heat. A body accreting from a mixture of metal and silicate material differentiates because denser iron-rich material sinks relative to lighter silicate material, provided the interior is warm enough (from accretion energy, radioactive decay, and impacts) for solid-like material to behave as a slow-moving fluid over geological time. The basic settling physics is captured by a Stokes-law sinking velocity for a dense blob of radius r and density ρm\rho_m moving through a less dense, viscous mantle of density ρs\rho_s…

Read this part in the article →

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.

Open the illustrated variables: a letter stands for a value guide →

See this notation across published equations →

The article lists its research sources here.