1.6. Shear Stress

Try these first

1. 1.

   What is shear stress?

   Hint

   Think about forces acting parallel to a surface.

2. 2.

   How is viscosity defined?

   Hint

   Consider how fluids behave when they flow.

3. 3.

   What is the formula for shear stress?

   • \\( \\tau = \\frac{F}{A} \\)
   • \\( \\tau = F \\times A \\)
   • \\( \\tau = \\frac{A}{F} \\)

   Hint

   Think of the relationship between force and area.

4. 4.

   True or False: In liquids, viscosity decreases with an increase in temperature.

   • True
   • False

   Hint

   Consider how heat affects fluid flow.

5. 5.

   A fluid with a viscosity of 0.75 Pa.s flows between two plates 5 cm apart. If the velocity gradient is 3 s⁻¹, calculate the shear stress and discuss its implications in fluid dynamics.

   Hint

   Use the shear stress equation we discussed.

6. 6.

   Calculate shear stress for a fluid where the viscosity is decreased from 0.7 Pa.s to 0.3 Pa.s while maintaining the same velocity gradient. What does this reveal about fluid behavior?

   Hint

   Reflect on the relationship between viscosity and shear stress.