How many times more heat will be released with the complete combustion of kerosene

How many times more heat will be released with the complete combustion of kerosene than with the complete combustion of wood of the same mass? Specific heat of combustion of kerosene 45 MJ / kg, firewood 10 MJ / kg.

Given:

m1 = m2 = m – the mass of kerosene and firewood is the same;

q1 = 45 MJ / kg = 45 * 10 ^ 6 J / kg – specific heat of combustion of kerosene;

q2 = 10 MJ / kg = 10 * 10 ^ 6 J / kg – specific heat of combustion of firewood.

It is required to determine Q1 / Q2 – how many times more heat energy will be released with complete combustion of kerosene than with complete combustion of firewood.

When kerosene is burned, energy will be released equal to:

Q1 = q1 * m1 = q1 * m.

When burning firewood, energy will be released, equal to:

Q2 = q2 * m2 = q2 * m.

Then:

Q1 / Q2 = q1 * m / (q2 * m) = q1 / q2 = 45 * 10 ^ 6 / (10 * 10 ^ 6) = 45/10 = 4.5.

Answer: when kerosene is burned, 4.5 times more energy will be released than when burning firewood.