Viscosity

Viscous Forces- These are forces which has tendency to oppose relative motion between different layers of liquid or gases.

Viscosity – Viscosity is the characteristic of a liquid due to which it opposes the relative motion between its various layers.

•    Viscosity is applicable to both liquid and gases.
•    The viscosity of a liquid is because of cohesive forces between layers.
•    Viscosity is liquid is less than viscosity of gases.
•    Solid has no viscosity.

Surface Tension

Cohesive Forces- Cohesive forces are the intermolecular forces, for example; hydrogen bonding and Van der Waals forces which cause a tendency in liquids to resist separation. These forces which are attractive forces exist between molecules of the same material. For example, rain falls as droplets, and not as fine mist, since water has strong cohesion hence its molecules pulls tightly together and droplets are formed. The cohesive force tends to bring closer molecules of a liquid, by making them comparatively large clusters which owes to molecules' dislike for its surrounding.

Floatation

Archimedes' Principle

•    The Archimedes' Principle is named after Archimedes of Syracuse
•    He discovered the law in 212 B.C.
•    The Archimedes' Principle states that any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.

Mathematically, the Archimedes' principle can be stated as Buoyancy = weight of displaced fluid.