Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Find Area of flattened gold with limited info.

  1. Jan 9, 2009 #1
    1. The problem statement, all variables and given/known data
    Gold, which has a density of 19.32 g/cm3, is the most ductile metal and can be pressed into a thin leaf or drawn out into a long fiber. (a) If a sample of gold with a mass of 1.708 g, is pressed into a leaf of 6.811 μm thickness, what is the area (in m2) of the leaf? (b) If, instead, the gold is drawn out into a cylindrical fiber of radius 2.100 μm, what is the length (in m) of the fiber?


    2. Relevant equations
    D = M/V
    V = LxWxH(thickness)

    3. The attempt at a solution
    So I have been working on this for quite a while now. Here is my attempt:

    I first solved D=M/V for V: V=M/D

    Then I plugged 1.708g/19.32g/cm^3 to find my volume of .088cm^3

    Then using Volume = L x W x H(thickness) I plugged in for volume and height and solved the equation.

    When I converted micrometers to centimeters my result was 6.811e-3cm.

    So (.088cm^3)/.006811cm = L x W (Area).

    After I found the area in cm^2 which the above result yields, I converted to meters^2 and got an answer of 1.29e-3m^2.

    It says it is wrong, where did I go wrong?
     
  2. jcsd
  3. Jan 9, 2009 #2

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    Your conversion for the thickness is wrong.
    1 um is 10^-3mm so 10^-4cm
     
  4. Jan 9, 2009 #3
    Alright thanks. That made all the difference, problem solved.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook