Question #a5b2a

2 Answers
Dec 25, 2017

The foil is only 0.0145mm thick! This is much less than 11000 of an inch!

Explanation:

You have to convert to a consistent set of units. We shall use grams for the mass unit and centimeters for the length unit.

The area of the foil is then

(75ft2)×(30.48cm1ft)2=69680cm2

The mass isj

(9.6oz)×(28.35g/oz)=272.2g

Now the volume of the foil is the mass divided by the density, and the density is given to only three significant figures. So we render the volume accordingly:

272.2g2.70gcm3=101cm3

And then the thickness is the volume divided by the area:

101cm369680cm2=0.00145cm=0.0145mm

Dec 25, 2017

1.45×102mm

Explanation:

The critical calculation here is the volume, after all of the conversions. The conversions are more tedious and a potential source of errors than anything relevant to the real question. We want a final answer in metric units (mm), so it may be best to first put all of the data into metric units at the millimeter level.

75ft2×92903.04=6967728mm2
http://www.endmemo.com/convert/area.php

1cm3=1000mm3
2.70gcm3×0.001cm3mm3=0.0027gmm3

9.6oz×28.35=272.16g
http://www.endmemo.com/convert/weight%20and%20mass.php
NOW we have:
Density: 0.0027g(mm)3
Mass: 272.16g
Area: 6967728mm2

The desired thickness calculation is:
T=MassDensity×Area = 272.160.0027×6967728 = 1.45×102