hydrometer.md

(Yellow‑zone draft)

Hydrometer#

Hydrometers measure fluid density via buoyancy. Simple in principle but sensitive to temperature and fluid composition.

Dimensional Core (SET)#

• Spin: not relevant
• Elec: none
• Temp: strongly affects density

Why Yellow‑Zone#

Direct measurement is good, but temperature and composition introduce mixed‑regime behavior.

Regime Notes#

• pos‑regime: uniform fluids, controlled temperature
• Q‑regime: mixtures, dissolved gases
• neg‑regime: turbulent or reactive fluids

Alignment Notes#

Needs explicit temperature and composition boundaries.