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Particle Density (packed Density)
{{refimprove, date=September 2016 The particle mass density or particle density of a material (such as particulate solid or powder) is the mass density of the particles that make up the powder. Particle density is in contrast to the ''bulk density'', which measures the average density of a large volume of the powder in a specific medium (usually air). The particle density is a relatively well-defined quantity, as it is not dependent on the degree of compaction of the solid, whereas the bulk density has different values depending on whether it is measured in the freely settled or compacted state (tap density). However, a variety of definitions of particle density are available, which differ in terms of whether pores are included in the particle volume, and whether voids are included. Measurement The measurement of particle density can be done in a number of ways: Archimedes' principle The powder is placed inside a pycnometer of known volume, and weighed. The pycnometer is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granular Material
A granular material is a conglomeration of discrete solid, macroscopic scale, macroscopic particles characterized by a loss of energy whenever the particles interact (the most common example would be friction when granulation, grains collide). The constituents that compose granular material are large enough such that they are not subject to thermal motion fluctuations. Thus, the lower size limit for grains in granular material is about 1 micrometre, μm. On the upper size limit, the physics of granular materials may be applied to ice floes where the individual grains are icebergs and to asteroid belts of the Solar System with individual grains being asteroids. Some examples of granular materials are snow, nut (fruit), nuts, coal, sand, rice, coffee, corn flakes, salt, and ball (bearing), bearing balls. Research into granular materials is thus directly applicable and goes back at least to Charles-Augustin de Coulomb, whose Friction, law of friction was originally stated for granul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boyle's Law
Boyle's law, also referred to as the Boyle–Mariotte law or Mariotte's law (especially in France), is an empirical gas laws, gas law that describes the relationship between pressure and volume of a confined gas. Boyle's law has been stated as: The absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if the temperature and amount of substance, amount of gas remain unchanged within a closed system.Levine (1978) p. 12 gives the original definition. Mathematically, Boyle's law can be stated as: or where is the pressure of the gas, is the volume of the gas, and is a Constant (mathematics), constant for a particular temperature and amount of gas. Boyle's law states that when the temperature of a given mass of confined gas is constant, the product of its pressure and volume is also constant. When comparing the same substance under two different sets of conditions, the law can be expressed as: P_1 V_1 = P_2 V_2. showi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porosity
Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure the "accessible void", the total amount of void space accessible from the surface (cf. closed-cell foam). There are many ways to test porosity in a substance or part, such as industrial CT scanning. The term porosity is used in multiple fields including pharmaceutics, ceramics, metallurgy, materials, manufacturing, petrophysics, hydrology, earth sciences, soil mechanics, rock mechanics, and engineering. Void fraction in two-phase flow In gas-liquid two-phase flow, the void fraction is defined as the fraction of the flow-channel volume that is occupied by the gas phase or, alternatively, as the fraction of the cross-sectional area of the channel that is occupied by the gas phase. Void fraction usually varies from location to l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bulk Density
In materials science, bulk density, also called apparent density, is a material property defined as the mass of the many particles of the material divided by the bulk volume. Bulk volume is defined as the total volume the particles occupy, including particle's own volume, inter-particle void volume, and the particles' internal pore volume. Bulk density is useful for materials such as powders, granules, and other "divided" solids, especially used in reference to mineral components (soil, gravel), chemical substances, pharmaceutical ingredients, foodstuff, or any other masses of corpuscular or particulate matter ( particles). Bulk density is not the same as the ''particle density'', which is an intrinsic property of the solid and does not include the volume for voids between particles (see: density of non-compact materials). Bulk density is an extrinsic property of a material; it can change depending on how the material is handled. For example, a powder poured into a c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archimedes' Principle
Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially, is equal to the weight of the fluid that the body displaces. Archimedes' principle is a law of physics fundamental to fluid mechanics. It was formulated by Archimedes of Syracuse. Explanation In '' On Floating Bodies'', Archimedes suggested that (c. 246 BC): Archimedes' principle allows the buoyancy of any floating object partially or fully immersed in a fluid to be calculated. The downward force on the object is simply its weight. The upward, or buoyant, force on the object is that stated by Archimedes' principle above. Thus, the net force on the object is the difference between the magnitudes of the buoyant force and its weight. If this net force is positive, the object rises; if negative, the object sinks; and if zero, the object is neutrally buoyant—that is, it remains in place without either rising or sinking. In simple words, Archim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambient Pressure
The ambient pressure on an object is the pressure of the surrounding medium, such as a gas or liquid, in contact with the object. Atmosphere Within the atmosphere, the ambient pressure decreases as elevation increases. By measuring ambient atmospheric pressure, a pilot may determine altitude (see pitot-static system). Near sea level, a change in ambient pressure of 1 millibar is taken to represent a change in height of . Underwater The ambient pressure in water with a free surface is a combination of the hydrostatic pressure due to the weight of the water column and the atmospheric pressure on the free surface. This increases approximately linearly with depth. Since water is much denser than air, much greater changes in ambient pressure can be experienced under water. Each of depth adds another bar (unit) , bar to the ambient pressure. Ambient-pressure diving is underwater diving exposed to the water pressure at depth, rather than in a pressure-excluding atmospheric diving suit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porosimeter
Porosimetry is an analytical technique used to determine various quantifiable aspects of a material's porous structure, such as pore diameter, total pore volume, surface area, and bulk and absolute densities. The technique involves the intrusion of a non-wetting liquid (often mercury) at high pressure into a material through the use of a porosimeter. The pore size can be determined based on the external pressure needed to force the liquid into a pore against the opposing force of the liquid's surface tension. A force balance equation known as Washburn's equation for the above material having cylindrical pores is given as: :P_L - P_G = -\frac :P_ = pressure of liquid :P_ = pressure of gas :\sigma = surface tension of liquid :\theta = contact angle of intrusion liquid :D_ = pore diameter Since the technique is usually performed within a vacuum, the initial gas pressure is zero. The contact angle of mercury with most solids is between 135° and 142°, so an average of 140° ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Pycnometer
A gas pycnometer is a laboratory device used for measuring the density—or, more accurately, the volume—of solids, be they regularly shaped, porous or non-porous, monolithic, powdered, granular or in some way comminuted, employing some method of gas displacement and the volume:pressure relationship known as Boyle's law. A gas pycnometer is also sometimes referred to as a helium pycnometer. The instrument invented by al-Bīrūnī, which functions on the principle of water volume displacement, is essentially the same as the modern pycnometer. The first known pictorial depiction of this device in the West can be traced to Wilhelm Homberg in 1699. Following the same method as al-Bīrūnī, Homberg noted that "the liquid is filled until it reaches just up to the tip of the small capillary tube." The pycnometer achieved its later accuracy through the work of Johann Heinrich Geißler (1815–1879). Types of gas pycnometer Gas expansion pycnometer Gas expansion pycnometer is also kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Powder (substance)
A powder is a dry solid composed of many very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms ''powder'' and ''granular'' are sometimes used to distinguish separate classes of material. In particular, ''powders'' refer to those granular materials that have the finer grain sizes, and that therefore have a greater tendency to form clumps when flowing. ''Granulars'' refer to the coarser granular materials that do not tend to form clumps except when wet. Types Many manufactured goods come in powder form, such as flour, sugar, ground coffee, powdered milk, copy machine toner, gunpowder, cosmetic powders, and some pharmaceuticals. In nature, dust, fine sand and snow, volcanic ash, and the top layer of the lunar regolith are also examples. Because of their importance to industry, medicine and earth science, powders have been studied in great detail by chemical engineers, mechanical engineers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density Gradient
Density gradient is a spatial variation in density over a region. The term is used in the natural sciences to describe varying density of matter, but can apply to any quantity whose density can be measured. Aerodynamics In the study of supersonic flight, Schlieren photography observes the density gradient of air as it interacts with aircraft. Also in the field of Computational Fluid Dynamics, Density gradient is used to observe the acoustic waves, shock waves or expansion waves in the flow field. Water A steep density gradient in a body of water can have the effect of trapping energy and preventing convection, such a gradient is employed in solar ponds. In the case of salt water, sharp gradients can lead to stratification of different concentrations of salinity. This is called a Halocline. Biology In the life sciences, a special technique called density gradient separation is used for isolating and purifying cells, viruses and subcellular particles. Variations of this inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyancy
Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus, the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the Displacement (fluid), displaced fluid. For this reason, an object with average density greater than the surrounding fluid tends to sink because its weight is greater than the weight of the fluid it displaces. If the objec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
