Question

142. В печи сгорели сухие дрова объёмом 0,01 м³ и торф массой 5 кг. Сколько теплоты выделилось в печи? Плотность дров 400 кг/м³.

Answer 1

Дано:

V = 0,01 м.³

m₂ = 5 кг.

ρ = 400 кг/м.³

q₁ = 8,3 * 10⁶ Дж/кг.

q₂ = 15 * 10⁶ Дж/кг.

Найти:

Q - ?

Решение:

Q₁ = q₁m₁ = q₁ρV

Q₁ = 8,3 * 10⁶ * 400 * 0,01 = 33,2 * 10⁶ Дж.

Q₂ = q₂m₂

Q₂ = 15 * 10⁶ * 5 = 75 * 10⁶ Дж.

Q = Q₁ + Q₂

Q = 33,2 * 10⁶ + 75 * 10⁶ = 10⁶ * (33,2 + 75) = 10⁶ * 108,2 Дж. = 108,2 МДж.

Ответ: 108,2 МДж.

Answer 2

Calculation of Heat Released

To calculate the amount of heat released in the oven, we need to consider the energy released from burning both the dry wood and the peat.

The heat released from burning dry wood can be calculated using the formula:

Q = m * c * ΔT

Where: - Q is the heat released - m is the mass of the dry wood - c is the specific heat capacity of dry wood - ΔT is the change in temperature

The heat released from burning peat can be calculated using the formula:

Q = m * c * ΔT

Where: - Q is the heat released - m is the mass of the peat - c is the specific heat capacity of peat - ΔT is the change in temperature

Let's calculate the heat released for both dry wood and peat separately.

Calculation for Dry Wood

Given: - Volume of dry wood: 0.01 m³ - Density of dry wood: 400 kg/m³

To find the mass of the dry wood, we can use the formula:

mass = density * volume

Substituting the given values:

mass = 400 kg/m³ * 0.01 m³ = 4 kg

Now, we need to find the specific heat capacity of dry wood. Unfortunately, I couldn't find the specific heat capacity of dry wood in the search results. However, we can assume a rough estimate of 2.5 kJ/kg°C for the specific heat capacity of dry wood.

Using the formula mentioned earlier, we can calculate the heat released:

Q = m * c * ΔT

Substituting the values: - m = 4 kg (mass of dry wood) - c = 2.5 kJ/kg°C (specific heat capacity of dry wood) - ΔT = unknown

Unfortunately, we don't have the change in temperature (ΔT) provided in the question. Without this information, we cannot calculate the exact amount of heat released from burning the dry wood.

Calculation for Peat

Given: - Mass of peat: 5 kg

Similar to the dry wood, we need to find the specific heat capacity of peat. Unfortunately, I couldn't find the specific heat capacity of peat in the search results. However, we can assume a rough estimate of 2.0 kJ/kg°C for the specific heat capacity of peat.

Using the formula mentioned earlier, we can calculate the heat released:

Q = m * c * ΔT

Substituting the values: - m = 5 kg (mass of peat) - c = 2.0 kJ/kg°C (specific heat capacity of peat) - ΔT = unknown

Unfortunately, we don't have the change in temperature (ΔT) provided in the question. Without this information, we cannot calculate the exact amount of heat released from burning the peat.

In conclusion, without the change in temperature (ΔT) provided, we cannot calculate the exact amount of heat released in the oven from burning the dry wood and peat.