Need help with these type of problems & if you answer could you explain

A 200-gal tank contains 100 gal of pure water. At time t = 0, a salt-water solution containing 0.5 lb/gal of salt enters the tan

Artyom0805 [142]

Answer:

1) $\frac{dy}{dt}=2.5-\frac{3y}{2t+100}$

2) $y(t)=(50+t)- \frac{12500\sqrt{2} }{(50+t)^{\frac{3}{2} }}$

3) 98.23lbs

4) The salt concentration will increase without bound.

Step-by-step explanation:

1) Let $y$ represent the amount of salt in the tank at time t, where t is given in minutes.

Recall that: $\frac{dy}{dt}=rate\:in-rate\:out$

The amount coming in is $0.5\frac{lb}{gal}\times 5\frac{gal}{min}=2.5\frac{lb}{min}$

The rate going out depends on the concentration of salt in the tank at time t.

If there is $y(t)$ pounds of salt and there are $100+2t$ gallons at time t, then the concentration is: $\frac{y(t)}{2t+100}$

The rate of liquid leaving is is 3gal\min, so rate out is $=\frac{3y(t)}{2t+100}$

The required differential equation becomes:

$\frac{dy}{dt}=2.5-\frac{3y}{2t+100}$

2) We rewrite to obtain:

$\frac{dy}{dt}+\frac{3}{2t+100}y=2.5$

We multiply through by the integrating factor: $e^{\int \frac{3}{2t+100}dt }=e^{\frac{3}{2} \int \frac{1}{t+50}dt }=(50+t)^{\frac{3}{2} }$

to get:

$(50+t)^{\frac{3}{2} }\frac{dy}{dt}+(50+t)^{\frac{3}{2} }\cdot \frac{3}{2t+100}y=2.5(50+t)^{\frac{3}{2} }$

This gives us:

$((50+t)^{\frac{3}{2} }y)'=2.5(50+t)^{\frac{3}{2} }$

We integrate both sides with respect to t to get:

$(50+t)^{\frac{3}{2} }y=(50+t)^{\frac{5}{2} }+ C$

Multiply through by: $(50+t)^{-\frac{3}{2}}$ to get:

$y=(50+t)^{\frac{5}{2} }(50+t)^{-\frac{3}{2} }+ C(50+t)^{-\frac{3}{2} }$

$y(t)=(50+t)+ \frac{C}{(50+t)^{\frac{3}{2} }}$

We apply the initial condition: $y(0)=0$

$0=(50+0)+ \frac{C}{(50+0)^{\frac{3}{2} }}$

$C=-12500\sqrt{2}$

The amount of salt in the tank at time t is:

$y(t)=(50+t)- \frac{12500\sqrt{2} }{(50+t)^{\frac{3}{2} }}$

3) The tank will be full after 50 mins.

We put t=50 to find how pounds of salt it will contain:

$y(50)=(50+50)- \frac{12500\sqrt{2} }{(50+50)^{\frac{3}{2} }}$

$y(50)=98.23$

There will be 98.23 pounds of salt.

4) The limiting concentration of salt is given by:

$\lim_{t \to \infty}y(t)={ \lim_{t \to \infty} ( (50+t)- \frac{12500\sqrt{2} }{(50+t)^{\frac{3}{2} }})$

As $t\to \infty$ , $50+t\to \infty$ and $\frac{12500\sqrt{2} }{(50+t)^{\frac{3}{2} }}\to 0$

This implies that:

$\lim_{t \to \infty}y(t)=\infty- 0=\infty$

If the tank had infinity capacity, there will be absolutely high(infinite) concentration of salt.

The salt concentration will increase without bound.

6 0

3 years ago

Matt plans to put concrete on a rectangular portion of his driveway. The portion is 8 feet long and 4 inches high. The price of

Lubov Fominskaja [6]

length = 8ft
height = 4 in
width = w ft --> u looking for this

convert in to ft for the height:

4 in (1 ft / 12 in) = 1/3 ft

You know that:
1 cubic yard = $ 98
? cubic yard = $58.07

Solve for ? cubic yard:
? cubic yard = 58.07/98 = 0.592551

convert this in cubic feet:
1 yard = 3 feet
0.59255 cubic yard (27 cubic ft/1 cubic yard) = 15.99887755 cubic ft

Now solve for the width:
length x width x height = ? cubic ft.
width = ? cubic ft / (length x height) =15.99887755 cubic ft/[(8ft)(1/3 ft )] = 5.999579082 ft

approx 6 ft

4 0

3 years ago

I need help!! It’s proving trapezoids theorems

sweet [91]

Because ABCD is an isosceles trapezoid, the angles A and D are congruent.

BA and CD are congruent (given) and AD is congruent to itself (reflexive property).

Then triangles BAD and CDA form a pair of SAS triangles, so they are congruent.

BD and CA are corresponding parts in those triangles, so they are congruent (CPCTC).

7 0

3 years ago

Read 2 more answers

Solve for x.<br><br> 0.5x + 78.2 = 287

vladimir2022 [97]

0.5x + 78.2 = 287
-78.2 -78.2

subtract 78.2 on both sides you will then get 0.5x = 208.8 you will then divide by 0.5 and the answer is x = 417.6

3 0

3 years ago

Read 2 more answers

Roy worked for 2 hours and earned $12. how many hours must he work at the same rate to earn $36? hours worked 2 ? dollars earned

kotegsom [21]

2hr=$12
1hr=12/2= $6/hr
$36=1hr/$6= 6hr for $36
If he worked 3hr he would get (6*3)= $18
If he worked 4 hours he would get (6*4)= $24
I hope this answers your question

7 0

3 years ago