Question

Известно, что сопротивление оборудования 120 Ом, он работает под напряжением 220В. Каков коэффициент полезного действия, если нагревается 1,5л воды, взятой при температуре 15С, закипает через 13 мин?

Answer 1

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Ответ
Объяснение

Answer 2

Calculation of the Efficiency of the Equipment

To calculate the efficiency of the equipment, we need to determine the amount of energy input and the amount of useful energy output.

Given: - Resistance of the equipment: 120 Ω - Voltage: 220 V - Amount of water heated: 1.5 liters - Initial temperature of the water: 15°C - Time taken for the water to boil: 13 minutes

To calculate the efficiency, we can use the formula:

Efficiency = (Useful energy output / Energy input) * 100

Determining the Energy Input

The energy input can be calculated using the formula:

Energy input = Power * Time

To find the power, we can use Ohm's Law:

Power = (Voltage^2) / Resistance

Substituting the given values:

Power = (220^2) / 120

Calculating the power:

Power = 48400 / 120

Power = 403.33 Watts

Now, we can calculate the energy input:

Energy input = Power * Time

Substituting the given values:

Energy input = 403.33 * (13 * 60) Energy input = 403.33 * 780 Energy input = 314,599.4 Joules

Determining the Energy Output

To determine the energy output, we need to calculate the change in thermal energy of the water.

The formula to calculate the change in thermal energy is:

Change in thermal energy = Mass * Specific heat capacity * Change in temperature

Given: - Mass of water = 1.5 kg (since 1 liter of water is approximately equal to 1 kg) - Specific heat capacity of water = 4.18 J/g°C (approximate value)

Converting the mass of water to grams:

Mass = 1.5 * 1000 = 1500 grams

Calculating the change in temperature:

Change in temperature = Final temperature - Initial temperature

The water boils at 100°C, so the final temperature is 100°C.

Change in temperature = 100 - 15 = 85°C

Now, we can calculate the change in thermal energy:

Change in thermal energy = Mass * Specific heat capacity * Change in temperature

Change in thermal energy = 1500 * 4.18 * 85

Change in thermal energy = 532,950 Joules

Calculating the Efficiency

Now that we have the energy input and the energy output, we can calculate the efficiency using the formula:

Efficiency = (Useful energy output / Energy input) * 100

Substituting the values:

Efficiency = (532,950 / 314,599.4) * 100

Efficiency = 169.5%

The calculated efficiency is 169.5%. However, it is important to note that this value is greater than 100%, which is not physically possible. It is likely that there is an error in the given information or calculations. Please double-check the values and calculations to ensure accuracy.

Please let me know if there's anything else I can help you with!