![]() The viscosity of water decreases smoothly from the freezing point while the density remains essentially constant except for the small maximum in density near 4☌. In cgs units the unit is called the centistoke. The kinematic viscosity is the dynamic viscosity divided by the density of the fluid. The unit centiPoise = 0.001 Pa s and is is sometimes written mPa s. These viscosities are at 20☌ except for the blood and blood plasma which are at body temperature, 37☌, and for steam which is at 100☌. The Poise is used in the table because of its more common usage. More commonly used is the dyne sec/cm 2 which is called Poise. Viscosity has the SI units Pascal seconds (Pa s) which is called the Poiseuille. Dynamic Kinematic Vapor Sound Density, Viscosity, p., Viscosity, v, Surface Tension, Pressure, Velocity, kg/m3 kg/m.s (x lo4) m2/s (x lo6) N/m (x lo2) Wa m/s Acetone 785 3.16 0.403 2.3 1 27.6 1174 Ammonia 608 2.20 0.362 2.13 910.0 Benzene 881 6.51 0.739 2.88 10.1 1298 Carbon disulfide 1272 Carbon tetrachloride 1590 9.67 0.608 2.70 1. When the cylinder is rotated, the water rises up to form a parabolic surface.Viscosity of Liquids and Gases Viscosity of Liquids and Gases Liquids Gage pressure = 2 * surface tension / radiusĥ. The gage pressure inside a soap bubble is given by the Laplace-Young equation: Pressure difference = density * gravity * height differenceĤ. The pressure difference between two points in a fluid is given by: = -147.6 kPa (Note: the negative sign indicates that the pressure is below atmospheric pressure)ģ. Since the pipe is frictionless and the velocity of water is constant, we can use Bernoulli's equation to relate the pressure and height: Substituting this value and the given dynamic viscosity into the formula, we get:Ģ. The density of air at 20☌ and 200 kPa can be found using the ideal gas law:ĭensity = (pressure * Mair) / (Ru * temperature) Kinematic viscosity = dynamic viscosity / density To find the kinematic viscosity of air, we use the formula: The kinematic viscosity of air at this state is: (Ru = 8.314 kJ/kmol.K, Mair = 28.96 g/mol)ġ. The dynamic viscosity of air at 20Â☌ and 200 kPa is 1.83x10-5 kg/m.s. If the water height inside the tank is 6 m, the resultant hydrostatic force on this wall is:ġ. ![]() The other side of the wall is open to the atmosphere. ![]() Consider the vertical rectangular wall of a water (density 1000 kg/m) tank with a width of 5 m and a height of 8 m. The height of water (specific weight = 9.810 N/L) at the center of the cylinder is:Ħ. The cylinder is rotated around its symmetrical axis at a constant speed of 15 rad/s. A 30-cm-diameter, 50-cm-high vertical cylindrical container is partially filled with 25-cm-high water. The gauge pressure inside a soap bubble of diameter 4 cm at 20Â☌ is:ĥ. The surface tension constant of soap water at 20Â☌ is 0.025 N/m. A water body has a depth of 10 m, the pressure difference between the water surface and a point located 5 m below the surface is (Take the density of water to be 1000 kg/m)Ĥ. The pressure at 19 m from the ground level is:ģ. Water (density 1.00 kg/L) flows in a frictionless vertical pipe the pressure is 340 kPa at 3 m from the ground level and the velocity of water does not change during this flow. The kinematic viscosity of air at this state is: (Ru = 8.314 kJ/kmol.K, Mair = 28.96 g/mol)Ģ. ![]()
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