Columnist Dave Barry poked fun at the name \"The Grand Cities,\" adopted by Gran
ID: 1285676 • Letter: C
Question
Columnist Dave Barry poked fun at the name "The Grand Cities," adopted by Grand Forks, North Dakota, and East Grand Forks, Minnesota. Residents of the prairie towns then named a sewage pumping station for him. Assume that at the Dave Barry Lift Station No. 16, untreated sewage is raised vertically by 5.54 m in the amount of 2.09 106 liters each day. With a density of 1,050 kg/m3, the waste enters and leaves the pump at atmospheric pressure through pipes of equal diameter.
(a) Find the output power of the lift station.
(b) Assume that a continuously operating electric motor with average power 5.90 kW runs the pump. Find its efficiency.
Explanation / Answer
time = 24*60*60 = 86400 s
density p = 1050 kg/m^3
volume v= 2090 m^3
m = p*v = 2.1945*10^6
P= m*g*h/t = 2.1945*10^6 *9.8*5.54/86400
P = 1.379 kW
b)
efficiency = output/input
1.379/5.90 = 0.2337
efficiency = 23.37 %