They also have weak intermolecular forces, which will make it easy for them to move past each other. This is because the molecules of water are relatively small. Therefore, liquids like honey, have higher viscosity values. Therefore, we can say that it is relatively low when we compare it to other liquids. This is caused by the frictional forces between the molecules of the liquid. Water viscosity refers to the fluid’s resistance to flow. Kinematic Viscosity: This is the measure of the flow of the fluid’s internal resistance as a result of the influence of the force of gravity.Hence, fluids move in the opposite direction at different speeds This is a force that is required by the fluid to defeat the internal molecular friction so that it can encourage the flow of the fluid. Dynamic Viscosity: This is the resistance to the flow of one layer of fluid in relation to the other.We have two types of viscosity: Dynamic and kinematic Therefore, we have dimension as ML -1T -1. Hence, by using η = F / (AV) we will have Where Force, F = Newtons = kgm/s 2 = MLT -2 We can derive the dimension of viscosity by applying the formula The derived standard international (SI) unit of dynamic viscosity is poiseiulle (PI). We measure viscosity in Newton seconds per meter square (Ns/m 2) or in Pascal seconds (Pas), and it’s a vector quantity. Η = Constant of proportionality called the coefficient of viscosity

Therefore, the force exerted between the two layers will be directly proportional to the velocity gradient and the surface area A.The velocities of adjacent layers A and B are V 1 and V 2 respectively.When layers of water flow slowly and steadily through a pipe, it will be observed that each layer flows at different velocities. The formula for calculating viscosity is:Ĭoefficient of viscosity, η = Force (F) / Viscosity Definition: What is the SI Unit of Viscosity and its Formula Therefore, we can say that viscosity is friction in liquids. Hence very cold thick palm oil is more viscous than very cold water. We consider liquids that pour slowly to be more viscous than those which pour faster. The thicker a liquid is, the higher its viscosity. Hence, honey tends to resist the motion of objects between its layers due to its thickness. We need to remember that friction is a force that resists motion. The honey is thicker and encourages more internal friction between its layers.

Therefore, the differences are due to the internal friction between the layers of the fluids.

Viscosity definition fluid mechanics