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A tank contains 240 liters of fluid in which 20 grams of salt is dissolved. Brine containing 1 gram of salt per liter is then pu

Novosadov [1.4K]

Answer:

$A(t)=240-220e^{-\frac{t}{40}}$

Step-by-step explanation:

A tank contains 240 liters of fluid in which 20 grams of salt is dissolved.

Volume of the tank = 240 liters
Initial Amount of Salt in the tank, A(0)=20 grams

Brine containing 1 gram of salt per liter is then pumped into the tank at a rate of 6 L/min

$R_{in}=$ (concentration of salt in inflow)(input rate of fluid)

$R_{in}=(1\frac{gram}{liter})( 6\frac{Liter}{min})=6\frac{gram}{min}$

$R_{out}=$ (concentration of salt in outflow)(output rate of fluid)

$R_{out}=(\frac{A(t)}{240})( 6\frac{Liter}{min})\\R_{out}=\frac{A}{40}$

Rate of change of the amount of salt in the tank:

$\dfrac{dA}{dt}=R_{in}-R_{out}$

$\dfrac{dA}{dt}=6-\dfrac{A}{40}$

We then solve the resulting differential equation by separation of variables.

$\dfrac{dA}{dt}+\dfrac{A}{40}=6\\$The integrating factor: e^{\int \frac{1}{40}dt} =e^{\frac{t}{40}}\\$Multiplying by the integrating factor all through\\\dfrac{dA}{dt}e^{\frac{t}{40}}+\dfrac{A}{40}e^{\frac{t}{40}}=6e^{\frac{t}{40}}\\(Ae^{\frac{t}{40}})'=6e^{\frac{t}{40}}$

Taking the integral of both sides

$\int(Ae^{\frac{t}{40}})'=\int 6e^{\frac{t}{40}} dt\\Ae^{\frac{t}{40}}=6*40e^{\frac{t}{40}}+C, $(C a constant of integration)\\Ae^{\frac{t}{40}}=240e^{\frac{t}{40}}+C\\$Divide all through by e^{\frac{t}{40}}\\A(t)=240+Ce^{-\frac{t}{40}}$

Recall that when t=0, A(t)=20 (our initial condition)

$20=240+Ce^{-\frac{0}{40}}\\20-240=C\\C=-220\\$Therefore, the number A(t) of grams of salt in the tank at time t\\A(t)=240-220e^{-\frac{t}{40}}$

3 0

2 years ago

The Fratellis will be arrested if and only if the police believe Chunk. Question 9 options: 1) p ↔ q 2) p ∨ q 3) p → q 4) ~p 5)

Amiraneli [1.4K]

Answer:

Option 1) p ←→ q

Step-by-step explanation:

The given statement is a combination of two phrases with a connective word.

Phrase 1 - The Fratellis will be arrested.

We consider this phrase as phrase p.

Phrase 2 - If the police believe chunk.

Phrase q.

Now these statements p and q are connected with a connecting word "If only and only".

When two phrases are connected by the connecting words "Only and only if", this connecting word is called as biconditional operator.

p (connecting word) q

p ( If and only if) q

p ←→ q

Therefore, Option 1) p ←→ q is the answer.

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Choose the correct written expression for: 25 – (3 x 4).

just olya [345]

Answer:

the quotient of 3 and 4 subtracted from 25.

Step-by-step explanation:

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Define sets and vectors

Afina-wow [57]

Answer:

set is a collection of distinct elements. vector is an element of a vector space.

Step-by-step explanation:

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2 years ago

Read 2 more answers

In 2012, there were about 313 million people in the United States, and just under 9 million of them had assets of $1 million or

zloy xaker [14]

New York has a density of millionaires more than twice that of the country as a whole. The density of millionaires is about the same for New York City as for the United States. Millionaires seem to prefer New York City to much of the rest of the United States. There is something in the water of New York City that encourages millionaires

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