How much kerosene is needed to operate a crane engine with an efficiency of 40% to lift

How much kerosene is needed to operate a crane engine with an efficiency of 40% to lift a concrete slab weighing 2 tons to a height of 15 meters.

Initial data: η (crane efficiency) = 40% = 0.4; h (the height to which the concrete slab was lifted) = 15 m; m1 (concrete slab weight) = 2 t = 2000 kg.

Reference values: q (specific heat of combustion of kerosene) = 4.6 * 10 ^ 7 J / kg; g (acceleration due to gravity) = 10 m / s2.

Efficiency of the crane: η = A / Q = ΔEp / Q = m1 * g * h / (m2 * q).

m2 = m1 * g * h / (q * η).

Let’s make a calculation: m2 = 2000 * 10 * 15 / (4.6 * 10 ^ 7 * 0.4) = 0.0163 kg or 16.3 g.

Answer: You will need to spend 16.3 g of kerosene.