Question

Для обогревания комнаты в зимнее время необходимо количество теплоты равное 300 МДж. Какая масса сухих дров необходима для этого? Сравни ее с массой нефти которой можно заменить дрова считая потери незначительными

Answer 1

Q=qm
m=Q/q
m=300 МДж/11 МДж/кг=27,27 кг
Q=300 МДж/44 МДж/к =6,81 кг


27,27/6,81 = в  4 раза  

Answer 2

Calculating the Mass of Dry Wood Needed for Heating:

To calculate the mass of dry wood needed to produce 300 MJ of heat, we can use the energy content of dry wood. The energy content of dry wood is approximately 20 MJ/kg.

Using the formula: Energy = Mass × Energy Content

We can rearrange the formula to solve for mass: Mass = Energy / Energy Content

Substituting the given energy requirement of 300 MJ and the energy content of dry wood, we get: Mass = 300 MJ / 20 MJ/kg

Calculating this gives us the mass of dry wood needed for heating.

Comparison with the Mass of Oil:

To compare the mass of dry wood with the mass of oil that can replace it, we can use the energy content of oil. The energy content of oil is approximately 42 MJ/kg.

We can use the same formula as before to calculate the mass of oil needed to produce 300 MJ of heat: Mass = Energy / Energy Content

Substituting the given energy requirement of 300 MJ and the energy content of oil, we get: Mass = 300 MJ / 42 MJ/kg

This will give us the mass of oil needed to produce the same amount of heat as the dry wood.

Results:

- The mass of dry wood needed for heating is approximately 15 kg. - The mass of oil needed to produce the same amount of heat is approximately 7.14 kg.

So, to produce 300 MJ of heat, you would need approximately 15 kg of dry wood, which is more than double the mass of oil needed to produce the same amount of heat.