1.9. Dynamic and Kinematic Viscosity

Try these first

1. 1.

   Define dynamic viscosity.

   Hint

   Think about how fluids react under stress.

2. 2.

   What units are used to express kinematic viscosity?

   Hint

   Consider how we relate dynamic viscosity and density.

3. 3.

   What is dynamic viscosity?

   • Resistance to flow
   • Density of fluid
   • Rate of flow

   Hint

   Think about how a thick syrup flows compared to water.

4. 4.

   True or False: Kinematic viscosity is defined as the ratio of dynamic viscosity to fluid density.

   • True
   • False

   Hint

   Recall the relationship between these two viscosities.

5. 5.

   You have a fluid flowing over a surface with an observed dynamic viscosity of 1.5 Pa.s and a flow velocity of 3 m/s. If the fluid has a density of 950 kg/m³, calculate the shear stress present.

   Hint

   Think about how shear stress is derived from viscosity and flow velocity.

6. 6.

   A thin layer of oil overlays water. The oil has a viscosity of 8.0 poise at 25°C. If the water is moving beneath it at 1 m/s, calculate the kinematic viscosity of the oil in m²/s.

   Hint

   Always convert units to standard SI before calculations.