- 13 A A New Pesticide Is Introduced To A Particular Region Where A Stream Becomes Contaminated With The Pesticide And 1 (92.13 KiB) Viewed 30 times
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13. a. A new pesticide is introduced to a particular region, where a stream becomes contaminated with the pesticide and flows into a 106 m² lake. The stream flows at a rate of 4000 m3/day with a concentration of 15 ng/m². Assuming that the lake is well-mixed and maintains a constant volume, then find the differential equation describing the concentration of this new pesticide in the lake. Solve this differential equation and find the limiting concentration in the lake. b. More realistically, the flow of the stream is seasonal and fluctuates over the year by about 40%. The lake still maintains an almost constant volume, but a better model for the concentration of a the pesticide in the lake is given by: dc = -0.001(4 – cos(0.0172t))(c – 15), dt with c(0) = 0. Solve this differential equation.