Question

На электроплитке мощностью 1261 Вт растопили 566 г льда с начальной температурой −13 °С. Полученную воду довели до кипения, причем 49 г её обратилось в пар. Процесс нагревания длился 47 мин. Найди КПД плитки. (Удельная теплота плавления льда λ =330000 Дж/кг, удельная теплота парообразования воды L =2260000 Дж/кг, удельная теплоёмкость льда с1 =2100 Дж/кг·°С и воды с2 =4200 Дж/кг·°С). Ответ (округли до сотых):

Answer 1

Ответ:

2260000-1261-566+13-49+47+330000+2100-4200=2300000

Answer 2

Calculation of Heat Energy:

To find the efficiency (КПД) of the electric stove, we need to calculate the heat energy supplied by the stove and compare it to the electrical energy consumed.

The heat energy required to melt the ice can be calculated using the specific heat of fusion (удельная теплота плавления) of ice (λ) and the mass of ice melted.

The heat energy required to heat the resulting water to its boiling point can be calculated using the specific heat capacity (удельная теплоёмкость) of ice (c1) and the change in temperature.

The heat energy required to convert the water to steam can be calculated using the specific heat of vaporization (удельная теплота парообразования) of water (L) and the mass of water converted to steam.

Finally, we can calculate the efficiency (КПД) by dividing the heat energy supplied by the stove by the electrical energy consumed.

Let's calculate each step:

1. Heat energy required to melt the ice: - Mass of ice melted: 566 g - Specific heat of fusion of ice: λ = 330000 J/kg

The heat energy required to melt the ice can be calculated using the formula: Heat energy = mass of ice melted * specific heat of fusion of ice

Heat energy required to melt the ice = 566 g * 330000 J/kg

2. Heat energy required to heat the water: - Initial temperature of the water: -13 °C - Specific heat capacity of water: c2 = 4200 J/kg·°C - Change in temperature: The water needs to be heated to its boiling point, which is 100 °C.

The heat energy required to heat the water can be calculated using the formula: Heat energy = mass of water * specific heat capacity of water * change in temperature

Heat energy required to heat the water = mass of water * specific heat capacity of water * change in temperature

3. Heat energy required to convert water to steam: - Mass of water converted to steam: 49 g - Specific heat of vaporization of water: L = 2260000 J/kg

The heat energy required to convert water to steam can be calculated using the formula: Heat energy = mass of water converted to steam * specific heat of vaporization of water

Heat energy required to convert water to steam = 49 g * 2260000 J/kg

4. Total heat energy supplied by the stove: The total heat energy supplied by the stove is the sum of the heat energy required to melt the ice, heat the water, and convert the water to steam.

Total heat energy supplied = Heat energy required to melt the ice + Heat energy required to heat the water + Heat energy required to convert water to steam

5. Electrical energy consumed: The electrical energy consumed can be calculated using the formula: Electrical energy consumed = Power of the electric stove * time

Electrical energy consumed = 1261 W * 47 min

6. Efficiency (КПД): The efficiency (КПД) of the electric stove can be calculated using the formula: Efficiency (КПД) = (Total heat energy supplied / Electrical energy consumed) * 100

Efficiency (КПД) = (Total heat energy supplied / Electrical energy consumed) * 100

Let's calculate the values and find the efficiency (КПД) of the electric stove.