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#### Crank

##### Full Member
5+ Year Member

Hey, if someone could help me out on this problem it would be greatly appreciated.

Question: Find the thickness of 75 square feet of aluminum foil weighing 340.2g, Al has density 2.70g/cm^3.

#### ozzi22

##### it's over 9000
7+ Year Member
Hey, if someone could help me out on this problem it would be greatly appreciated.

Question: Find the thickness of 75 square feet of aluminum foil weighing 340.2g, Al has density 2.70g/cm^3.
thickness= mass/density*area
mass= 340.2g
density= 2.70g/cm^3
area= 75 square feet
thickness= 340.2g/2.70g/cm^3*75cm^2=1.68cm

#### Crank

##### Full Member
5+ Year Member
** answer has to be in mm btw**

a) 1.8 x 10^-2

b) 5.5 x 10^-1

c) 1.3 x 10^-1

d) 2.2 x 10^-5

e) 3.2 x 10^-2

Last edited:

5+ Year Member
x2 post

its (a)

Last edited:

#### ozzi22

##### it's over 9000
7+ Year Member
340.2g/2.70g/cm^3= 126cm^3
convert 75 square feet to cm^2= 69677.28cm^2
***126cm^3/69677.28cm^2= 0.001808337cm
*** convert to mm= 0.0180837mm****
ans.= 1.8*10^-2mm

#### liveoak

##### Full Member
try to use the power of units on this type of question. you know you'll need an answer in terms of length, so find a way to chop off the "g" and "Cm^2" and it becomes a bit easier.