4.2. Velocity Gradient and Shear Rate

Try these first

1. 1.

   Define velocity gradient in your own words.

   Hint

   Think about how fluid velocity changes across a distance.

2. 2.

   What does shear stress represent?

   Hint

   Consider how forces act on surfaces in fluid dynamics.

3. 3.

   What defines a Newtonian fluid?

   • Viscosity changes with temperature
   • Viscosity remains constant regardless of shear rate
   • Viscosity is only a function of pressure

   Hint

   Think about how viscosity responds to different conditions.

4. 4.

   True or False: In non-Newtonian fluids, viscosity is constant.

   • True
   • False

   Hint

   Remember the effects leading to changes in viscosity.

5. 5.

   A fluid flows through a 1 cm thick layer between stationary and moving plates at 10 m/s. Calculate the shear stress if the viscosity is 0.8 Pa.s.

   Hint

   Remember the shear stress formula involving viscosity.

6. 6.

   Discuss the implications of temperature variations on the viscosity of honey compared to air when heated.

   Hint

   Think about how molecular interactions change with temperature.