Having a problem with a fairly early Physics with Calculus 1 problem

[frankfjf]

Hi all, been a while since I posted here needing homework help but it's a new semester and I'm already stumped (much to my shame :shy: ) Anyway, I am presented with the following problem:

Gold, which has a mass of 19.32 g for each cubic centimeter of volume, is the most ductile metal and can be pressed into a thin leaf or drawn out into a long fiber. (a) If 9.000 oz of gold, with a mass of 27.63 g/oz, is pressed into a leaf of 1.000 mm thickness, what is the area (in m^2) of the leaf? (b) If, instead, the gold is drawn out into a cylindrical fiber of radius 2.900 mm, what is the length (in m) of the fiber?

I have already solved part a, but am uncertain how one solves part b? I just need a hint or two to get started on the right direction. Do I just convert the units accordingly or do I need to obtain more information first? I was able to solve part a by simply converting the 9 oz. of gold into cubic centimeters using the information given and then further converting from there, but that doesn't seem to work for part b, unless I did my math wrong somewhere. Please help! Thanks!

 

[frankfjf]

Still stumped... can't anyone help?

 

[andrewchang]

find the mass of the gold, and change it into volume. now divide this volume by the cross section area of the wire. make sure to use the right units.

 

[Stephan Hoyer]

The formula for a volume of a cylinder is V=pi*r²*L. Since you have already calculated the volume of gold (V), and are given the radius (r), it should be simple to find the length of the fiber (L).

 

[frankfjf]

Thanks for your help!