8.4. Virtual Fluid Balls Concept

Try these first

1. 1.

   What happens to shear stress in a fluid at rest?

   Hint

   Think about fluid motion—if it's not moving, what happens to forces acting parallel to surfaces?

2. 2.

   What is gauge pressure?

   Hint

   Consider how we compare pressures to the atmosphere.

3. 3.

   What is the pressure at a point in fluid when at rest?

   • Only shear stress
   • Only atmospheric pressure
   • Only normal stress

   Hint

   Think about the definition of shear stress.

4. 4.

   True or False: Gauge pressure is always higher than vacuum pressure.

   • True
   • False

   Hint

   Consider the definitions of both types of pressure.

5. 5.

   A dam contains water up to a height of 10 meters. Calculate the gauge pressure at the base of the dam (assume density = 1000 kg/m³).

   Hint

   Use the basic formula for hydrostatic pressure.

6. 6.

   A mercury barometer shows a height of 760 mm. Calculate the atmospheric pressure in Pascals.

   Hint

   Help yourself with the conversion of units and correct unit density for mercury.