Viscosity and Surface Tension

Surface tension, capillary action, applications

  1. Surface tension is the property of a liquid's surface to resist external forces and minimize its surface area.
  2. It is caused by the cohesive forces between liquid molecules, which are stronger at the surface.
  3. The SI unit of surface tension is newton per meter (N/m).
  4. Surface tension enables the formation of spherical droplets in liquids like water and mercury.
  5. Capillary action is the ability of a liquid to flow in narrow spaces without external forces like gravity.
  6. It occurs due to

Viscosity, Stokes’ law, terminal velocity

  1. Viscosity is a measure of a fluid's resistance to flow, caused by internal friction between fluid layers.
  2. Fluids with higher viscosity flow more slowly, while those with lower viscosity flow more freely.
  3. The SI unit of viscosity is the pascal-second (Pa·s), and the CGS unit is the poise.
  4. Newtonian fluids obey Newton’s law of viscosity, where shear stress is directly proportional to the rate of shear strain.
  5. Non-Newtonian fluids do not follow Newton’s law
Viscosity and Surface Tension