4.5.1. Control Volume and Momentum Equations

Try these first

1. 1.

   Explain the concept of mass conservation.

   Hint

   Think about balance in a jar.

2. 2.

   What is a control volume?

   Hint

   It can be visualized as a box or container.

3. 3.

   What is the formula for mass conservation in a control volume?

   • Inflow = Outflow
   • Mass = Volume x Density
   • Total Force = Mass x Acceleration

   Hint

   Remember this is the balance of mass.

4. 4.

   True or False: Incompressible flow indicates changes in density.

   • True
   • False

   Hint

   Think about liquids, are they compressible?

5. 5.

   A water jet strikes a stationary flat plate at a velocity of 15 m/s. Calculate the force on the plate if the area of the jet impact is 0.2 m².

   Hint

   Calculate flow rate before substituting.

6. 6.

   Consider a control volume with a moving boundary at 5 m/s that encounters a water jet at 20 m/s. Find the thrust if the jet area is 0.5 m².

   Hint

   Use inflow velocity reduction by the moving boundary.