In: Civil Engineering

Consider a lake with 65 × 106 m2 of surface area for which the only source of phosphorous is the effluent from a wastewater treatment plant. The lake is receiving a flow rate of 1 m3/s from the wastewater treatment plant, which has a phosphorous concentration of 20 mg/L. The lake is also fed by a stream having 20 m3/s of flow with no phosphorous in it. If the phosphorous settling rate is estimated to be 10 m/yr. (a) Write down the phosphorous mass balance equation for the lake and draw a control volume diagram for the lake showing influent streams, effluent streams, point-discharge source. (b) Estimate the average phosphorous concentration in the lake at steady-state. (c) Bonus Q: What level of phosphorous removal at the treatment plant would be required to keep the average lake concentration below 0.02 mg/L?

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An airplane has an effective wing surface area of 19.0 m2 that
is generating the lift force. In level flight the air speed over
the top of the wings is 55.0 m/s, while the air speed beneath the
wings is 35.0 m/s. What is the weight of the plane?

Question 4
The capillary surface area of a child 10 years old is 1.14 m2,
of an adult woman is 1.6 m2, and of an adult, man is 1.9 m2. The
pulmonary blood volume per area is 271 ml/m2. Capillary blood
volume varies between 20% and 25% of the pulmonary blood
volume.
a) Assuming capillaries are 8 um in diameter and have an average
length of 1 mm, calculate the range of the number of open
capillaries in the lung...

An 80-kg person whose surface area is 1.30 m2 worked
for one hour at a distance of 2.0 meters from a
spherically-symmetric source of radiation whose output power is
0.35 W. What dose (in rads) did he receive?

A plane of area 0.25m2and surface charge density s=4.5 nC/m2
lies in the x = 0.00 m plane, and a second plane of surface charge
density s= -4.50 nC/m2 lies in the x = 0.0200 m plane. Find:a.find
the capacitance, the stored charge, and the potential energy of the
system. b.the electric potential difference between the 2
planes.c.the electric field at (i) x = 0.0180 m and (ii) x = 0.0500
m (508 N/C and 0 N/C). d.What is the...

Which of the following describes the process by which the
surface area of a component is hardened in such a way that leaves
the core of that component softer and tougher?
Age hardening
Case hardening
Quenching
Annealing

Consider a residential heat pump that uses lake water as the
heat source in the winter and as heat sink inthe summer. The house
is to maintained at a winter temperature of T= 18 degrees C and a
summer temperature of T= 25 degrees C. To do this efficiently, it
is found that the indoor coil should be at T= 50 degrees C in the
winter and T= 5 degrees C in the summer. The outdoor coil
temperature can be...

The mass m1 on a smooth table is connected to the
mass m2 which moves only in the vertical direction by an
inextensible L length rope passing through a hole in the table.
Answer the following by ignoring the friction in the system.
a) What are the generalized coordinates of the system. Write the
Lagrangian of the system using these coordinates.
b) Find the conservative values of the system.
c) Obtain the Lagrange equations of the system and discuss what...

Assume that the only source of systematic risk in the economy is
the market risk. Consider a portfolio (P) with the following
characteristics (which were measured over a certain timeperiod T):
mean or expected annual return (µp) = 100%, standard deviation of
annual portfolio returns (σp) = 25% and a beta relative to the
market (βp) = −1. During the same time-period T, the market index
(M) had the following characteristics: mean or expected annual
return (µm) = 33% and...

1) Animals vary in size, which is largely due to surface
area-to-volume ratios. Explain what surface area to volume ratios
are and why this is important for animals. Give three examples from
three different phyla of structures that were gained or lost due to
surface area volume ratio.
2) Flight has evolved independently three times in the
animal kingdom. Compare and contrast the three different evolved
forms of flight in the animal kingdom. Discuss the groups they
evolved in and...

1. Which of the following structures is intended to maximize the
surface area available for gas exchange?
a. Thin membranes lining respiratory organs such as gills and
lungs.
b. Multiple infoldings of respiratory surfaces, such as lamellae
in gills.
c. Inhaled fresh air is mixed with old air from the previous
breathing cycle.
d. Blood circulates in counter current direction to water flow
in gills.
-------------------------------------
2. The affinity of hemoglobin for oxygen changes with pH. What
is affecting the...

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