Question

Сколько теплоты выделится при полном сгорании сухих сосновых дров объёмом 3 метра в кубе?

Answer 1

Q = q * m

q - удельная теплота сгорания топлива ( для сухих сосновых дров 10,2 МДж / кг = 10200000 Дж)
m - масса 

Вычисляем массу:

m = p * V

p - плотность ( для сухих сосновых дров 550 кг / м3)
V - объём ( 3 м3)

m = 550 * 3 = 1650 кг

Теперь можно приступить к количеству теплоты:

Q = 10200000 * 1650 = 16830000000 Дж = 16830 МДж

Answer 2

Calculating Heat Released from Burning Pine Logs

To calculate the heat released from burning pine logs, we can use the formula Q = qm, where Q is the heat released, q is the heat of combustion, and m is the mass of the fuel burned. The heat of combustion for pine wood is approximately 17.9-20.5 MJ/kg

Given that the volume of the pine logs is 3 cubic meters, we need to calculate the mass of the wood burned to determine the heat released.

Calculating the Mass of Pine Logs

To calculate the mass of the pine logs, we can use the density of pine wood, which is approximately 470-580 kg/m^3

Using the formula m = V * ρ, where m is the mass, V is the volume, and ρ is the density, we can calculate the mass of the pine logs.

m = 3 m^3 * 470-580 kg/m^3 m ≈ 1410-1740 kg

Calculating the Heat Released

Now that we have the mass of the pine logs, we can calculate the heat released using the formula Q = qm.

Given q = 17.9-20.5 MJ/kg and m ≈ 1410-1740 kg, we can calculate the range of heat released.

Using the lower bound of heat of combustion (17.9 MJ/kg): Q = 17.9 MJ/kg * 1410 kg Q ≈ 25239 MJ

Using the upper bound of heat of combustion (20.5 MJ/kg): Q = 20.5 MJ/kg * 1740 kg Q ≈ 35670 MJ

Therefore, the heat released from burning the 3 cubic meters of dry pine logs ranges from approximately 25,239 to 35,670 megajoules.

This calculation is based on the heat of combustion and the estimated mass of the pine logs.

I hope this helps! If you have further questions, feel free to ask.