Anonymous asked in Science & MathematicsPhysics · 4 years ago

The third (current-carrying) rail of a subway track is made of steel and has a cross-sectional area of about 13 cm2 .?

What is the resistance of 18 km of this track? The resistivity of steel is 1×10−7 Ω·m.

Answer in units of Ω.

1 Answer

  • Steve
    Lv 7
    4 years ago
    Favorite Answer

    a = 13/10000 = 0.0013 m²

    R = L*ρ/a = 18E3*1E-7/0.0013 = 1.38 Ω

    Source(s): My 'cheat sheet' of physics formulae
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