Question 1132652
L is length;

If 0.2 cm "thickness" means "diameter, then volume is  {{{pi*(0.2/2)^2*L}}}
or {{{pi*L*0.1^2=pi*L*0.01=highlight_green(0.01L*pi)}}} cubic centimeters.


Now you need to use the density for copper.  You find that yourself and use it.   You are given, 1 kilogram of copper.

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If your reference source tells  8.96 grams per cubic centimeter is density for copper then you have what you need.



You were given 1 kilogram of copper, which is  1000 grams of copper.
 

{{{(1000*grams)/(0.01L*pi*cm^3)=8.96(grams/cm^3)}}}


{{{1000/(0.01*L*pi)=8.96}}}

SOLVE FOR L.