Volume and surface area of a cylinder

[Paulo Serrano]

Homework Statement

I need the ratio like in the image below
http://img228.imageshack.us/img228/4015/foiessa.jpg
I guess as a function of D.

Homework Equations

Volume of a cylinder: pi*r^2*h
Area: 2*pi*r*(h+r)

The Attempt at a Solution

No clue.

 

[Integral]

You have expressions for the area and volume, you are told to compute the ratio

\frac {Volume} {Area}

What is your problem?

 

[Arshad_Physic]

The area of a cylinder, as far as I remember, is: 2*pi*r*h +(2*pi*r^2)

 

[Arshad_Physic]

Now find the the volume, and divide that by area.

V= d^2*pi*h

A= (2*pi*d*h) + (2pi*d^2)

And now write V/A = (d^2*pi*h)/[(2*pi*d*h) + (2pi*d^2)]

I hope I am right, and that it helps! :)

 

[Integral]

That is a good start. Now do some simplification.

 

[Paulo Serrano]

d isn't the radius though.