Question

Помогите по экзамену пожалуйста Определите мощность электрического чайника, если в нем за 20 мин 1,4 кг воды нагревается от 20С до 100С при КПД 60%

Answer 1

А1=100-20=80
t=20мин
P=A1/t
P=80\20
P=4Квт

Answer 2

Calculation of Power of Electric Kettle

To determine the power of an electric kettle, we can use the formula:

Power (P) = Energy (E) / Time (t)

Where: - Power (P) is measured in watts (W) - Energy (E) is measured in joules (J) - Time (t) is measured in seconds (s)

In this case, we need to find the power of the electric kettle based on the given information.

Given: - Mass of water (m) = 1.4 kg - Initial temperature (T1) = 20°C - Final temperature (T2) = 100°C - Efficiency (η) = 60% - Time (t) = 20 minutes = 20 * 60 seconds = 1200 seconds

To calculate the energy (E) transferred to the water, we can use the formula:

Energy (E) = mass (m) * specific heat capacity (c) * temperature change (ΔT)

The specific heat capacity of water is approximately 4.18 J/g°C.

Let's calculate the energy transferred to the water first:

Energy (E) = 1.4 kg * 4.18 J/g°C * (100°C - 20°C)

Converting the mass to grams and simplifying the equation:

Energy (E) = 1.4 kg * 1000 g/kg * 4.18 J/g°C * 80°C

Now, let's calculate the power (P) using the formula mentioned earlier:

Power (P) = Energy (E) / Time (t)

Substituting the values:

Power (P) = (1.4 kg * 1000 g/kg * 4.18 J/g°C * 80°C) / 1200 seconds

Calculating the power:

Power (P) = 1.4 kg * 1000 g/kg * 4.18 J/g°C * 80°C / 1200 seconds

Simplifying the equation:

Power (P) = 1.4 * 1000 * 4.18 * 80 / 1200 W

Calculating the result:

Power (P) = 192 W

Therefore, the power of the electric kettle is 192 watts.