Stupid Math ...

[ss3079]

Got a cylinder with no top.
250 square cm's of fiberglass.

r cm's would represent the base radius of this cylinder. What is the cubic function? What are the dimensions of the cylinder when it has 200mL in it? Not only what is it, how did you get it ... this could really come in handy later on for me.

I was thinking along the lines of V=pir^2h ... C=2r ... = 2pir+pir^2 ... whaaaaat the ...

What this has to do with boxes ... you shall see.

Much appreciated.

- Steve

[ss3079]

And if you don't know the height, or any dimensions ... where I'm confused.

- Steve

[ss3079]

I need to know the cubic function of a cylinder with no top made out of 250 cm^2 of fiberglass, or metal, whatever. First of all.

- Steve

[jbl_marshall21]

You don't know any dimensions, but you need a cylinder to handle 200 mL ?

so screwed. steve if u get boggled up, i took geometry last year (passed wit a 91) but i'm sure u know what ur doing. :veryhappy

[ss3079]

so screwed. steve if u get boggled up, i took geometry last year (passed wit a 91) but i'm sure u know what ur doing. :veryhappy

So this guy makes a can with 250cm^2 of metal, fiberglass, whatever ... with no top.
So you let r cm's represent the base radius. What is the volume of the can as a cubic function of r ?

Im really confused.

- Steve

[Wonderbread]

you want a function for the volume of the cylinder with a surface area of 250 cm^2... it's a **** good thing I understand Stevenglish...

[ss3079]

you want a function for the volume of the cylinder with a surface area of 250 cm^2... it's a **** good thing I understand Stevenglish...

Yeah well thats as good as it gets

- Steve

[Wonderbread]

not sure if this is right...
you never know, lol.

V = (Pi*r^2)[(250-Pi*r^2)/p]

Pi = Pi...
r= radius
p = perimeter

[jbl_marshall21]

So this guy makes a can with 250cm^2 of metal, fiberglass, whatever ... with no top.
So you let r cm's represent the base radius. What is the volume of the can as a cubic function of r ?

Im really confused.

- Steve

SA=250cm^2

thats without a top. hmmm tricky let me think here. aah yes nah nevermind i can't remember the the surface area formula of a cylinder.

its right on the tip of tounge. ****'t if u don't figure it out tonight i'll get it tomorrow. i'll see if my math teacher can get it cuz i don't remember the **** formula. wait is it circumference X height + the area on the bottom?

[ss3079]

Thanks much ... we'll see if it works.

- Steve

[jbl_marshall21]

not sure if this is right...
you never know, lol.

V = (Pi*r^2)[(250-Pi*r^2)/p]

Pi = Pi...
r= radius
p = perimeter

perimeter on a cylinder????????

[ss3079]

Who knows, I'm pretty confused right now ...

A can with no top is made from 250cm^2 of fiberglass. 'r' cm's would rep. the base radius of the can. Need the volume of the can as a cubic function of 'r'.

I've gotten things scribbled down here ...
SA= 250cm^3 = Pi*r^2 + 2Pi*r*h
V= h*Pi*r^2
V= (Pi*r^2)[(250-Pi*r^2)/p)
V= 250r - Pi*r^3 / 2

Last one catches my eye. But why, and how ...

- Steve

[Wonderbread]

Surface Area of a Cylinder = 2 pi r^2 + s r h
Surface Area = Areas of top and bottom +Area of the side

Surface Area = 2(Area of top) + (perimeter of top)* height
Surface Area = 2(pi r^2) + (2 pi r)* h

250 = (pi*r^2) + [(2pi*r)*h]
Isolate for ‘h’
h = [(250-pi*r^2)/(2pi*r)]

V=Pi*r*h
V = pi*r * [(250-pi*r^2)/(2pi*r)]

There… ass….

[awalbert88]

Uhm...

I'm going to go grab a soda and then come back to this one. I think I need some caffeine if I'm going to understand this.

[Wonderbread]

I took off the top in my calculations... hence me not multiplying by 2... ***.. :p there is a bottom to the cylinder.