Differential Equations Compartmental Analysis Word Problem

In summary, the problem involves pumping fresh water into a 60-gallon tank initially filled with brine, with the mixture overflowing into a second tank and eventually spilling onto the ground. The task is to determine when the water in the second tank will taste the saltiest and how salty it will be compared to the original brine. The equations for this problem are: ds/dt = input - output and du/dt = previous output - output. The solution involves finding the time when the output and input rates are equal, which is 20 minutes, and using the formula 1/e to determine the saltiness of the water in the second tank.
  • #1
pwood
5
0
Hello, I am trying to tackle a word problem in differential equations, but the setup has flummoxed me. Thank you in advance to any advice/help given.

Homework Statement



Beginning at time t  0, fresh water is pumped at
the rate of 3 gal/min into a 60-gal tank initially filled
with brine. The resulting less-and-less salty mixture
overflows at the same rate into a second 60-gal tank
that initially contained only pure water, and from
there it eventually spills onto the ground. Assuming
perfect mixing in both tanks, when will the water in
the second tank taste saltiest? And exactly how salty
will it then be, compared with the original brine?


Homework Equations


ds/dt = input - output

du/dt = previous output - output


The Attempt at a Solution


I have included a picture of a scratch piece of paper I am working on to demonstrate my work.
 

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  • #2
I should have mentioned that the stated answer is 20 minutes, for part one, and 1/e for part 2.
 

What is a differential equation?

A differential equation is a mathematical equation that describes how a variable changes over time. It involves the rate of change of a variable in relation to itself or other variables.

What is compartmental analysis?

Compartmental analysis is a method used in mathematical modeling to describe the flow of material or energy between different compartments, or regions, in a system. It is often used to model biological systems such as the distribution of drugs in the body.

How do you solve a word problem involving differential equations and compartmental analysis?

The first step in solving a word problem involving differential equations and compartmental analysis is to identify the compartments and their corresponding variables. Then, write out the differential equations that relate the variables to each other. Finally, solve the equations using appropriate techniques such as separation of variables or Laplace transforms.

What are some real-life applications of differential equations and compartmental analysis?

Differential equations and compartmental analysis have many real-life applications, such as modeling drug distribution in the body, predicting population growth, and analyzing chemical reactions. They are also used in fields such as physics, economics, and engineering to model complex systems.

What are some techniques used to solve differential equations?

Some common techniques used to solve differential equations include separation of variables, Laplace transforms, and series solutions. Other methods such as numerical approximation and software programs can also be used to solve differential equations.

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