The kinematic viscosity v defined by the ratio of the dynamic viscosity µ to the density ρ of the fluid: T: tangential stress kinematic viscosity of water s – 1) in a direction y (in m) perpendicular to the sliding plane :.The dynamic (or absolute) viscosity µ defined by the ratio of the tangential shear stress T (in Pa) to the speed gradient V (in m There are two types of viscosity: Dynamic viscosity of water The kinematic viscosity n is equal to the ratio of the molecular viscosity of the fluid to its density. Viscosity varies inversely with temperature. Liquids have a higher viscosity than gases: the molecules are closer to gas: the molecules are closer together, bonds are established between them which increase the cohesion of the whole. Molecular viscosity is denoted by µ it is expressed in N.s.m-2. The addition of a small amount of suspended or dissolved substance can greatly increase the viscosity of the liquid. Measurement of the resistance of a fluid to change of shape: viscosity determines the speed of movement of the fluid (for example, the speed of movement of a spoon in a bowl: the more viscous the liquid, the slower the movement). If the temperature drops, it's the other way around. If the temperature rises, the molecules of the fluid move apart and the density decreases. It corresponds to the number of molecules contained in the volume. It is the measure of the mass present in a certain quantity of fluid. The gases tend to occupy all the available space they are compressible. Liquids are generally considered to be non-compressible they keep the same volume whatever their shape. Its shape is preserved only if a solid body limits it. Liquid water is a fluid, a deformable substance without its own form, which changes shape under the action of an external force applied to it. Animals and plants that light can walk or move over “skin” surface water.Density and viscosity of water Density and viscosity of water There is only attraction that leads to the fluid and leading to the side only, and power was causing a tension in the surface layer of the water.Īt this water level there will be a voltage also forming a kind of “skin” surface. Only against adjacent molecules on the surface alone is not the case. Affinity to each of these molecules into every corner, the average is the same. On the surface contact with the air, there are few water molecules that escape from its bond with other molecules called evaporation. In the liquid phase, the power of attraction is still large enough so that the molecules of the liquid substance still want to get together, which is called the nature of cohesion within the liquid. Water molecules that have affinity towards neighboring molecules, although they have a tendency to move on their own. Water surface tension arising from the activity of water molecules that are not balanced on and below the surface of the water. This shows that the viscosity of water can determine:ī) body shape (morphology) of aquatic animals.ĭ) It is a major barrier to the movement. The viscosity of water is approximately 100 times greater than in the air, water animals have to cope with greater pressure when compared to the animals that live in the air.
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