A wastewater is discharged through an outfall to a freshwater stream of mean velocity 0.1 m/s. The DO upstream of the outfall is 8.5 mg/L. The saturation (maximum) DO for the river water is 9.2 mg/L. After the wastewater mixes with the stream flow, the ultimate BOD of the mixed flow at the point of discharge is 25 mg/L. Assuming the deoxygenation rate k1 = 0.25 d-1 and the reaeration rate k2 = 0.4 d^-1. Determine:
a. The time (tc) and distance downstream (xc) where DO is a minimum.
b. The minimum DO.

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

In general, how do thermosetting plastics compare to thermoplastics in mechanical and physical properties?

Abarometer contains mercury with a density of 13600 kg/m3. atmospheric conditions are 95.8 kpa and 20 °c at 20 °c, the vapor pressure of the mercury is 0.000173 kpa. the column of mercury will rise to a height of most nearly. select one: a)- 0.38 m b)- 0.82 m c)- 0.48 m d)- 0.72 m