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September 14th, 2009, 06:47 PM   #1
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Word problem

A sheet of metal is 29.4 mm wide and 16.1 mm long. If it weighs 4.093 g and the density of the metal is 7.23 g/cm3, what is the thickness of the sheet (in mm)?

What I found out...


Here's how I worked this problem:

The Density Conversion:

7.23g/cm^3 / 10mm = 0.723 g/mm^3

The volume calculation:

V = m/d
V = 4.093g / 0.723 g/mm^3 = 5.66 mL

The rearrangement:

V = (29.4mm)(16.1mm)t

t = (5.66mm) / (29.4mm) * (16.1mm)
= 0.011957578mm


This doesn't seem correct to me however, did I work this question correctly?
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September 14th, 2009, 07:51 PM   #2
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Re: Word problem

Quote:
7.23g/cm^3 / 10mm = 0.723 g/mm^3
This in incorrect. To convert from g/cm^3 to g/mm^3, you must divide by 10^3, not 10.
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September 14th, 2009, 08:36 PM   #3
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Re: Word problem

Quote:
Originally Posted by mathman
Quote:
7.23g/cm^3 / 10mm = 0.723 g/mm^3
This in incorrect. To convert from g/cm^3 to g/mm^3, you must divide by 10^3, not 10.
Alright I have reworked this problem as such:


7.23 g/cm^3 / 1000 = 0.00723

V = M / D
V = 4.093 / 0.00723
V = 566.113463

V = (29.4)(16.1)*t

t = 566.113463 / (29.4)(16.1)
t = 1.19mm


Are all these units correct here and the rework itself? Thanks for catching that error BTW.
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September 15th, 2009, 04:48 PM   #4
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Re: Word problem

I have not checked the arithmetic, but the procedure looks correct.
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