Question

Related Rates Problem

Answer 1

Ill post my work next

Answer 2

Here

Answer 3

I'm not all that good at related rates... and I have absolutely no idea how to do your problem...
but have you tried getting a r to h ratio so you can replace an r with an h or an h with an r into v = 1/3 pi r^2 h to make the problem easier?

Answer 4

yeah ive solved for everything except r' aka: (dr/dt)

Answer 5

yeah... hit the same wall before... http://openstudy.com/users/jeffsours#/updates/535e8c33e4b0b5bc4da6fb13
couldn't find dr/dt
so you have to get ratio of radius to height
to get just two variables in the v = 1/3 pi r^2 h equation

Answer 6

yeah i got 4 of the 6 variables, if i could figure out how to pull dr/dt i could solve

Answer 7

pulling dr/dt out of there means taking out r from the original equation...
like IF the ratio was r = 3h
then you can get V = 1/3 pi (3h)^2 h simplify, derive and won't have to deal with the dr/dt

Answer 8

erm... also, for 2.75/9 = x/5 -> x = 13.75/9 right? :/

Answer 9

2.75/9 = 11/36
r in terms of h -> 36h/11
plug in for r...
V=1/3 pi r^2 h --> V = 1/3 pi (36h/11)^2 h
--> V = (432/121) pi h^3
-> dV/dt = (1296/121) pi h^2 (dh/dt)
= (1296/121) pi (5)^2 (20)
= (648000/121)pi
-> (648000/121)pi + 7300 is what I got :/ idk if it right tho...