25.4. Example Problems

Try these first

1. 1.

   What happens to pressure at the exit of a pipe flowing into the atmosphere?

   Hint

   Think about atmospheric conditions.

2. 2.

   Define hydraulic gradient line.

   Hint

   Reflect on open channel flows.

3. 3.

   What does the hydraulic gradient line represent?

   • Water Surface
   • Energy
   • Pressure

   Hint

   Consider what is visible in open channels.

4. 4.

   True or False: An energy gradient line is always above the hydraulic gradient line.

   • True
   • False

   Hint

   Think of what each line represents.

5. 5.

   Given a pipe with a diameter halved at the midpoint, derive the velocity change and calculate the pressure difference based on Bernoulli's equation.

   Hint

   Consider how area impacts velocity.

6. 6.

   A turbine extracts 1000 J of energy from water and operates with 80% efficiency. Calculate the input energy needed.

   Hint

   Think of the definition of efficiency.