Problem Diagram



The flow rate of the faucet is given by Q = umAm

The float of the rotameter is 10 mm from its base (i.e., y =10 mm). Hence, the area of the annular space is


The mean velocity of the water passing through the annular space is given by


The volume and frontal area of the ball are calculated to be

Now, the mean velocity um can be calculated as


The volume flow rate is thus given by

     Q = (1.05 m/s)(15.9 mm2) = 16.7 (10-6) m3/s

The total volume of the water wasted in a 30-day period is
      Vtotal = (16.7)(10-6)(30)(24)(60)(60) = 43.3 m3

The corresponding cost is
   = (43.3 m3) ($1.75/1000 gal) (1 gal/0.003785 m3)
   = $20.02

Practice Homework and Test problems now available in the 'Eng Fluids' mobile app
Includes over 250 problems with complete detailed solutions.
Available now at the Google Play Store and Apple App Store.