Density
The density at all points of a homogeneous object equals its total mass divided by its total volume. The mass is normally measured with a scale or balance; the volume may be measured directly (from the geometry of the object) or by the displacement of a fluid. To determine the density of a liquid or a gas, a hydrometer, a dasymeter or a Coriolis flow meter may be used, respectively. Similarly, hydrostatic weighing uses the displacement of water due to a submerged object to determine the density of the object.
Flotation of flexible objects
Consider two plates of infinite width, thickness formula_2, and length formula_3 that are connected by a torsional spring with spring constant per unit width formula_4. Furthermore, let formula_5 be the angle between a plate and the horizontal, and formula_6 the from where the meniscus meets the plate to the horizontal. The distance from the undisturbed water line to the plate's outer edge is formula_7. The density of water is formula_8, the density of air is considered negligible, and the plate density, formula_9, shall be varied. All systems naturally assume a configuration that minimizes total energy. Thus, the goal of this analysis is to identify the configurations (i.e., values of formula_7 and formula_5) that result in a stable equilibrium for a given value of formula_9.