Density Mass per unit volume

Density and Specific Gravity. Water has a density, mass per unit volume, of about 62.4 lb/fU (1.000 g/cc) at 0°C, whereas mercury, also a Hquid, has a density of about 842 lb/ft (13.5 g/cc) at the same temperature. AH things being equal, greater densities mean thicker required tank sheU thicknesses. 

Equation 10-5 is the unsteady, three-dimensional mass eonservation or eontinuity equation at a point in a eompressible fluid. The first term on the left side is the rate of ehange in time of the density (mass per unit volume). The seeond term deseribes the net flow of mass leaving the element aeross its boundaries and is ealled the eonveetive term. 

Density Mass per unit volume of a substance, usually expressed in units of g/cm. ... 

A second unexpected property of water is that it expands when it freezes. Water has its maximal density, mass per unit volume, at 4°C. As it is cooled further, it begins to expand. Ice at 0°C occupies about 11% more volume than does liquid water at the same temperature. In this respect water is nearly unique. Almost all other liquids contract when they freeze, as we would expect since the solid phase is generally more compact and more ordered than the liquid phase and, hence, is denser. This behavior is not just a laboratory curiosity the fact is that our life on this planet is dependent on this remarkable property. This point has been elegantly stated by L. J. Henderson, a leading biochemist in the early twentieth century, in his thoughtful book The Fitness of the Environment which he wrote in 1913 Here are his words. 

To separate isotopes by this process, they must be in the gaseous form. Therefore, the separation of isolopes of uranium required the conversion of die metallic uranium into a gaseous compound, for which purpose the hexafluoride. UF. was chosen. Since the atomic weight of fluorine is 19, die molecular weight of the hexafluoride of 235 LI is 235 + (6 19) = 349, and the molecular weight of die hexafluoride of 23SU is 238 + (6 x 19) = 352. Since the rate of diffusion of a gas is inversely proportional to die square root of its density (mass per unit volume), the maximum separation factor for one diffusion process of the uranium isotopes is V352/349 = 1.0043, Since only part of the gas can be allowed to diffuse, the, actual separation factoi is even less dian this theoretical maximum. 

Specific gravity it is heated. Shrink film gives good protection to the products packaged and has excellent clarity. The density (mass per unit volume) of any material divided by that of water at a standard temperature, usually 4 °C. Since water s density is nearly 1.00 g/cc, density in g/cc and specific gravity are numerically nearly equal. 

The number of network strands per unit volume (number density of strands) is p = njV. In the last equality, p is the network density (mass per unit volume), Mg is the number-average molar mass of a network strand, and IZ is the gas constant. The network modulus increases with temperat-iire hpnaiisp its origin is entropic, analogous to the pressure of an ideal gas p = nkTjV. The modulus also increases linearly with the number density of network strands u = n/V = pJ fEquation (7.31) states that the modulus of any network polymer is kT per strand. 

The Kelvin equation can be combined with the relative humidity, RH, if water is involved as the fluid relative humidity indicates how moist the air is. The amount of water vapor in the air at any given time is usually less than that required to saturate the air. The relative humidity is the percentage of saturation humidity, generally calculated in relation to the saturated vapor density. Relative humidity may be defined as the ratio of the water vapor density (mass per unit volume) to the saturation water vapor density, usually expressed in percent. Relative humidity is also approximately equal (exactly equal when water is assumed as an ideal gas) to the ratio of the actual water vapor pressure to the saturation water vapor pressure, RH = PJP°. The P° values corresponding to each temperature are given in tables which can be found in handbooks. If RH is measured in an experiment, then Pv can be calculated by using the saturation water vapor pressure tables and can be inserted into the Kelvin equation. 

If p is the density (mass per unit volume) of k and v. velocity of species/ component k, then the local variation of is given by... 

Here Xn is the Flory solvent-polymer interaction parameter and p is the network density (mass per unit volume). The volume fraction of the polymer in the swollen state can be easily determined experimentally by measuring the volume of the swollen sample Vs and of the dry sample 02 = Vd/Vsw... 

Density lden(t)-ss-te (1603) (absolute density) Mass per unit volume of a substance. The SI unit is kg/m, but others in common use are g/cm, Ib/ft, and Ib/gallon. It is an important criterion in specifying some plastics, e.g., polyethylene, which can vary in density from 0.92 to 0.98 g/cm, with significant associated variation in properties such as modulus. Since density decreases with rising temperature, the temperature of measurement should be stated. See www.astm.org for current... 

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