How much dry firewood needs to be burned to release 15GJ of energy?

These tasks: Q (required amount of heat from burning dry wood) = 15 GJ.

Reference values: q (specific heat of combustion of dry wood) = 10 MJ / kg = 10 * 10 ^ 6 J / kg.

SI system: Q = 15 GJ = 15 * 10 ^ 9 J.

The required mass of dry firewood is determined from the formula: Q = q * m; m = Q / q.

Let’s make the calculations: m = 15 * 10 ^ 9 / (10 * 10 ^ 6) = 1500 kg or 1.5 tons.

Answer: You will need to burn 1.5 tons of dry wood.