Task data: t1 (initial water temperature) = 10 ºС; t2 (end temperature) = 60 ºС; m2 (mass of consumed firewood) = 1 kg; heat losses are not taken into account.
Reference values: Sv (specific heat capacity of water) = 4200 J / (kg * ºС); q (specific heat of combustion of wood) = 1 * 107 J / kg.
We express the mass of water that can be heated by burning 1 kg of firewood from the equality: q * m2 = Cw * m1 * (t2 – t1), whence m1 = q * m2 / (Cw * (t2 – t1)).
Calculation: m1 = 1 * 107 * 1 / (4200 * (60 – 10)) = 47.62 kg.
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