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 Thread Tools Display Modes Sep 21st 2019, 06:35 PM #1 Physics Junior Member   Join Date: Sep 2019 Location: Canada (at the moment) Posts: 1  I've been trying to get the right answer but it doesn't work! This problem is from Chemistry and Chemical Reactivity, 8th Edition. A spool of copper wire has a mass of 4.26 kg. How long is the wire in the spool if the wire has a diameter of 2.2 mm? (The density of copper is 8.96 g/cm^3. The answer is 130 m, but I keep getting 1.2*10^2 m. Am I doing something wrong, or is there something wrong with the book? Here is my work (some parts may be wrong because I am typing what I wrote on paper): ? g = 4.26 kg * 1000 g / 1 kg = 4.26*10^3 g ? g/m^3 = 8.96 g/cm^3 * 9*10^6 g/m^3 / 1 g/cm^3 = 8.96*10^6 g/m^3 V = m/D = 4.26*10^3 g / 8.96*10^6 g/m^3 = 4.75*10^-4 m^3 ?m = 2.2mm * .001 m / 1 mm = 2.2*10^-3 m r = d/2 = 2.2*10^-3 m / 2 = 1.1*10^-3 m h = V/πr^2 = 4.75*10^-4 m^3 / ((1.1*10^-3)^2)π m^2 = 1.2*10^2 m (The answer before applying 2 significant figures is around 125.) Last edited by Physics; Sep 21st 2019 at 10:06 PM. Reason: Meant to say diameter is 2.2 mm, not 4.2 mm  Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode 