What useful work does a heat engine, the efficiency of which is 40%, perform when burning 1 ton of charcoal?

Data: m (mass of charcoal burnt) = 1 t; η (heat engine efficiency) = 40% or 0.4.

Reference values: q (specific heat of combustion of charcoal) = 34 * 10 ^ 6 J / kg.

SI: m = 1 t = 10 ^ 3 kg.

The useful work that a heat engine can perform is determined from the formula for calculating the efficiency: η = A / Q = A / (q * m), whence A = η * q * m.

Calculation: A = 0.4 * 34 * 10 ^ 6 * 10 ^ 3 = 13.6 * 10 ^ 9 J = 13.6 GJ.

Answer: When burning 1 ton of charcoal, the heat engine will perform work of 13.6 GJ.