The resistance of a copper wire is twice that of aluminum, and the mass is four times less. Determine which wire is longer and by how many times. Density of copper um = 8.9 103 kg/m3, aluminum yal = 2.7 103 kg/m3; resistivity of copper rm = 0.01 μOhm m, aluminum ral = 0.028 μOhm m.

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