[ahawk1]

To the alchemists, gold was the material representation of purity. It is a very soft metal that can be hammered into extremely thin sheets. If a 1.15 g piece of gold is hammered into a sheet whose area is 38.4 ft2, what is the average thickness of the sheet? (The density of gold is 19.32  g/cm3.)

for some reason im just not figuring this out, i think im doing something really stupid. thanks for the help in advance.

[macman104]

What is the definition of volume when related to area?  V = Area * ___?

[ahawk1]

What is the definition of volume when related to area?  V = Area * ___?

v=area*height?

[macman104]

Yup, and you need the height, so make it your x.  Now, what is the equation for density, do you see how you can plug in your volume formula (with your x), and then solve for x?  All the other values are given to you.  Also, make sure your units match before you do this!

[ahawk1]

Yup, and you need the height, so make it your x.  Now, what is the equation for density, do you see how you can plug in your volume formula (with your x), and then solve for x?  All the other values are given to you.  Also, make sure your units match before you do this!

ok so when converting the 38.4 ft^2 to cm^2 i would get 35674.8cm^2 or 34560?

[macman104]

Show your working.

[ahawk1]

Show your working.

19.32g/cm^3=1/1.15g*34560cm^2*hcm

19.32=30052.17391h
h=6.4288e-04cm?

[macman104]

Setup is correct, but you had a question about the conversion from ft^2 to cm^2, I was saying post that calculation.

[ahawk1]

Setup is correct, but you had a question about the conversion from ft^2 to cm^2, I was saying post that calculation.

38.4ft^2*(900cm^2/1ft^2)

[macman104]

You should use 1 ft = 30.48cm not 30cm, it's an exact value (based on 1 inch = 2.54 cm is an exact value as well).

[ahawk1]

You should use 1 ft = 30.48cm not 30cm, it's an exact value (based on 1 inch = 2.54 cm is an exact value as well).

hmmm using that i get h=6.228e-4cm and that is still incorrect

[macman104]

Sorry, not quite correct.  When you substitute the formula for volume in, you should get:

Density = Mass/Area*Height

You had:

Density = 1/Mass*Area*Height

Rearranging should have given you:

Height = Density*Area/Mass

[ahawk1]

Sorry, not quite correct.  When you substitute the formula for volume in, you should get:

Density = Mass/Area*Height

You had:

Density = 1/Mass*Area*Height

Rearranging should have given you:

Height = Density*Area/Mass

thanks for sticking with me. my algebra skills have failed for me once again. i got that problem right now,  thanks very much!