Equation 5 · Part 3 · From Origins to Frontier: A History of Planetary Science and Exploration
Symbol r^2
What this part means
The square of r: multiply r by itself.
Its job in the formula
occurs above the fraction bar. The numerator is divided by the entire denominator below it.
Full expression→Symbol r^2→Article meaning
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 moving through a less dense, viscous mantle of density …
Learn the underlying idea
An exponent tells how a base is used in multiplication. In x³, x is the base and 3 is the exponent: x³ = x × x × x.
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