In a main line consisting of a copper wire with a cross-section of S1 = 5 mm2, it is necessary to include a lead fuse at a temperature of t = 25°C, which would melt when the wire is heated to dt = 20°C. Find the fuse cross section. Specific heat capacity of copper c1 = 0.36 kJ/(kg K), lead c2 = 0.12 kJ/(kg K). Melting temperature of lead tmelt = 327°C, specific heat of fusion of lead L = 2.4·104 J/kg. Resistivity of copper p1 = 0.017 μOhm m, lead p2 = 0.21 μOhm m. Density of copper y1 = 8.9 103 kg/m3, lead density y2 = 11.4 103 kg/m3.

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