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6 votes
1 answer
2k views

Volume vs. Surface Area Integrals

In order to find the volume of a sphere radiud $R$, one way is to slice it up into a stack of thin, concentric disks, perpendicular to the $z$-axis. a disk at any point $z$ will have radius $r=\sqrt{R^...
Dylan's user avatar
  • 16.6k
1 vote
2 answers
85 views

Is the area independent of $n$? $ A=\int_0^\infty \frac{e^{-\frac{1}{tn}}(e^{-tn}(tn+1))}{t}~dt $

Consider the parametric equation $x=\frac{1}{t}e^{-tn}$ and $y=te^{-\frac{1}{tn}}.$ To integrate under this curve I put it in the proper form: $$ A=\int_0^\infty \frac{e^{-\frac{1}{tn}}(e^{-tn}(tn+1))}...
zeta space's user avatar
0 votes
2 answers
963 views

"Present value and accumulated value of money flow" problem

Find the present value and accumulated value after 10 years for an income stream with the rate of money flow $f(t) = 200 + 150t$ dollars per year and the rate of interest 12% compounded continuously. ...
arcbloom's user avatar
  • 2,062
0 votes
1 answer
4k views

UNRESOLVED: Pushing oil out of a tank using work integration

I have a tank of oil with a density of $900\frac{kg}{m^3}$. My tank has a spout that is $2$ meters tall and the general radius of the tank is $6$ meters. It is half full of oil and I want to find the ...
Computer's user avatar
  • 575