Surface area representing a cell as an idealized sphere of radius "r", the volume and surface area are, respectively, "V" = 4/3 π "r"; "SA" = 4 π "r". The resulting surface area to volume ratio is therefore 3/"r". Thus, if a cell has a radius of 1 μm, the SA:V ratio is 3; whereas if the radius of the cell is instead 10 μm, then the SA:V ratio becomes 0.3. With a cell radius of 100, SA:V ratio is 0.03. Thus, the surface area falls off steeply with increasing volume. Surface area The surface area of a solid object is a
Solid nitrogen of Pluto. The thermal conductivity of solid nitrogen is 0.7 W m K. Thermal conductivity varies with temperature and the relation is given by "k" = 180.2×T watts per kelvin. Specific heat is given by 926.91×e joules per kilogram per kelvin. Its appearance at 50 K is transparent, while at 20 K it is white. Nitrogen frost has a density of 0.85 g cm. As a bulk material the crystals are pressed together and density is near that of water. It is temperature dependent and given by ρ = 0.0134"T" − 0.6981"T" + 1038.1 kg/m. The volume coefficient of expansion