Newtonian and non newtonian systems

Newtonian and non-Newtonian systems refer to how substances respond to forces and deformations.

• Definition: Newtonian systems follow Newton's laws of viscosity. For these substances, the viscosity (resistance to flow) is constant and doesn't change with the rate of shear (how fast the layers of the substance move relative to each other).
• Example: Water and air are typical Newtonian fluids. If you stir water faster, it resists motion in the same way regardless of how quickly you're stirring.

 Non-Newtonian Systems:

• Definition: Non-Newtonian systems do not follow Newton's laws of viscosity. Their viscosity changes with the rate of shear. This means that the substance's resistance to flow can vary depending on how fast or slow you apply force.
• Types:
  • Shear-thickening fluids: These become more viscous (thicker) when subjected to higher shear rates. An example is cornstarch mixed with water.
  • Shear-thinning fluids: These become less viscous (thinner) under higher shear rates. Examples include ketchup and paint.
  • Bingham plastics: These behave like a solid until a certain yield stress is applied, after which they flow like a liquid. Toothpaste is a common example.

In summary, Newtonian systems have a constant viscosity, while non-Newtonian systems exhibit varying viscosities depending on the conditions.