Stokes' Law describing partial sedimentation is given by:
Rate = [(gd^2)(Δρ)]/18η
where g = 9.81 m s^-2 is gravitational acceleration. Δρ is the density difference between particles and the air, air viscosity of η = 1.67E-4 g cm^-1 s^-1 and d is the particle diameter in centimeters.
a. Calculate the weight(g) of one cubic centimeter of air at 1.0 atm and 15 degrees celsius.
b. Assume particles have a density of 2.45 g cm^-3 and are being released by a 100 m smokestack. How long does it take (s) a 25μm particle to settle to the ground?
c. It rains exactly once a week. What is the smallest particle size (μm) that can settle to the grounds before wet removal?
Solution Preview
a. Calculate the weight(g) of one cubic centimeter of air at 1.0 atm and 15 degrees celsius.
if we use the equation alluded to in: http://hypertextbook.com/facts/2000/RachelChu.shtml (Center choice) as "The density of moist air may be determined by a similar relation:
D = 1.2929 (273.13/T) [(B - 0.3783e)/760] where T is the absolute temperature; B, the barometric pressure in mm, and e the vapor pressure of the moisture in the air in mm."
Then in our circumstance D = ...
Solution Summary
Solution to problem involving sedimentation/settling rates of airborne particles as per Stoke's Law.
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1) The bulk modulus of a gas varies with pressure. In the case of the air, the bulk modulus of air is equal to 1.40 times its pressure. the atmospheric pressure at sea level is 1.01 * 105 N/m2. The density of air at sea level is 1.20 kg/m3. For these conditions, what is the speed of sound as it passes through the air?
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