# Length of tinfoil

1. May 10, 2010

### JUSTaROCK

1. The problem statement, all variables and given/known data
Aluminum, which has a mass of 2.7 grams for each cubic centimeter of volume, can be rolled into thin sheets
which your grandparents probably called "tinfoil." If a lump of aluminum of mass 0.75 kg is rolled into such a
sheet 18 μm thick and 25 cm wide, approximately how long is this roll of "tinfoil?"

2. Relevant equations

v = m/p p = density
v = L * A
surface area of circle = 4pi(r)^2
area of circle = pi(r)^2

3. The attempt at a solution

I have spent alot of time on this problem but i can't seem to get it right i do not know what to do with the width or the thickness. I have tried to play it off like the width is the diameter,(which seems possible), but i just don't know what to do i have been working on this problem for 2 days now and i can't figure out what to do with it, please help i have a final on this tomorrow and i see it alot in the old exams so i would like to know how to approach it if the problem gives thickness and width.

2. May 10, 2010

### zachzach

Think about the sheet of the foil before you roll it up. What shape is it?

3. May 10, 2010

### JUSTaROCK

rectangle? so find the area of it as a rectangle ok ha ha don't know why i never thought of that

4. May 10, 2010

### zachzach

A rectangle yes, but you are interested in the volume since the density is mass over volume.