Wires of what length can be made from a piece of copper weighing 40 kg if the cross-sectional

Wires of what length can be made from a piece of copper weighing 40 kg if the cross-sectional diameter of the wire is 1.2 mm ^ 2. Find also the resistance of these wires.

Data: m (mass of the used piece of copper) = 40 kg; d (cross-sectional diameter of the manufactured wire) = 1.2 mm (in SI d = 1.2 * 10 ^ -3 m).

Constants: ρ (specific electrical resistance of copper) = 0.017 Ohm * mm2 / m; ρm (copper density) = 8900 kg / m3.

1) Determine the length of the manufactured wire: l = V / S = m / (ρm * 0.25 * Π * d ^ 2) = 40 / (8900 * 0.25 * 3.14 * (1.2 * 10 ^ – 3) ^ 2) = 3976 m.

2) We calculate the resistance: R = ρ * l / S = ρ * l / (0.25 * Π * d ^ 2) = 0.017 * 3976 / (0.25 * 3.14 * 1.2 ^ 2) = 59 , 8 Ohm.