Question

сколько кг воды можно нагреть на 20градусах, затратив 20 кВт •ч энергии, если только 87% энергии идёт на нагревание воды? ответ дать в кг

Answer 1

объяснение :

вода закипает в 100 градусах, поэтому 100°С - 20°С.

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Answer 2

Calculating the Amount of Water Heated

To calculate the amount of water that can be heated by 20 degrees using 20 kW•h of energy, with only 87% of the energy going towards heating the water, we can use the following formula:

Q = mcΔT

Where: - Q is the amount of heat energy transferred to the water (in joules) - m is the mass of the water (in kilograms) - c is the specific heat capacity of water (in joules per kilogram per degree Celsius) - ΔT is the change in temperature (in degrees Celsius)

First, let's calculate the amount of heat energy transferred to the water using the given energy and efficiency.

Calculating the Heat Energy Transferred

The formula to calculate the heat energy transferred is:

Q = P * t

Where: - Q is the heat energy transferred (in joules) - P is the power (in watts) - t is the time (in hours)

Given: - P = 20 kW = 20,000 W - t = 1 hour

Using the formula, we can calculate Q:

Q = 20,000 W * 1 hour = 20,000 J

Calculating the Amount of Water Heated

Now, let's calculate the amount of water that can be heated using the calculated heat energy and the specific heat capacity of water.

The specific heat capacity of water, c, is approximately 4200 J/kg°C.

We can rearrange the formula Q = mcΔT to solve for m:

m = Q / (c * ΔT)

Given: - Q = 20,000 J - c = 4200 J/kg°C - ΔT = 20°C

Substituting these values into the formula:

m = 20,000 J / (4200 J/kg°C * 20°C) ≈ 0.238 kg

So, the amount of water that can be heated by 20 degrees using 20 kW•h of energy, with only 87% of the energy going towards heating the water, is approximately 0.238 kilograms.