definition of viscosity

[SOHAWONG]

In a question,I found a unit call 'viscosity',but i don't what it is
can anyone explain the definition,I have no idea of this completely,THX

[tiny-tim]

Hi SOHAWONG! Welcome to PF! :wink:

Solids have friction.

Fluids (liquids and gases) have viscosity.

Both measure the resistance to movement.

The main difference between friction and viscosity is that when an object moves against a solid, the solid stays where it is, but when an object moves through a fluid, some of the fluid moves with the object.

See http://en.wikipedia.org/wiki/Viscosity for details. :smile: