Question

При помощи нагревателя мощностью кВт N=16,8 кВт в течение с τ=20 с нагревают некоторый объём воды. Чему равен этот объём V, если температура этой порции воды увеличилась на С Δt=40∘С? Ответ выразить в л л, округлив до целых. Удельная теплоёмкость воды равна Дж кг С c=4200 Дж/(кг⋅∘С). Плотность воды равна кг м ρ=1000 кг/м3. Потерями энергии пренебречь. Определите энергию, вырабатываемую нагревателем. Ответ выразить в кДж, округлив до целых. Определите массу m воды. Ответ выразить в кг, округлив до целых.​

Answer 1

Ответ:

2 л          336 кДж

Объяснение:

N=16,8*10³ Вт    τ=20 с    ρ=10³ кг/м³    Δt=40°   c=4200 Дж/(кг*С)   V=?

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N=Q/τ

Q=c*m*Δt

m=ρ*V

N*τ=c*ρ*V*Δt

V=N*τ/(c*ρ*Δt)=16,8*10³*20/(4200*10³*40)≈0.002 м³

Q=N*τ=16,8*10³*20=336*10³ Дж

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Answer 2

Calculation of Volume of Water Heated

To calculate the volume of water heated by a heater with a power of 16.8 kW for a duration of 20 seconds, we can use the formula:

Q = mcΔt

Where: - Q is the heat energy supplied by the heater (in Joules) - m is the mass of water (in kilograms) - c is the specific heat capacity of water (in J/(kg⋅°C)) - Δt is the change in temperature (in °C)

We can rearrange the formula to solve for the mass of water:

m = Q / (cΔt)

Given: - Power of the heater, N = 16.8 kW - Duration of heating, τ = 20 seconds - Change in temperature, Δt = 40 °C - Specific heat capacity of water, c = 4200 J/(kg⋅°C)

First, let's convert the power from kilowatts to joules per second:

N = 16.8 kW = 16,800 J/s

Next, let's calculate the heat energy supplied by the heater:

Q = N × τ = 16,800 J/s × 20 s = 336,000 J

Now, we can calculate the mass of water:

m = Q / (cΔt) = 336,000 J / (4200 J/(kg⋅°C) × 40 °C)

Simplifying the equation:

m = 336,000 J / (168,000 J/kg) = 2 kg

Therefore, the volume of water heated is 2 liters (rounded to the nearest whole number).

Calculation of Energy Generated by the Heater

To determine the energy generated by the heater, we can use the formula:

Energy = Power × Time

Given: - Power of the heater, N = 16.8 kW - Duration of heating, τ = 20 seconds

Let's convert the power from kilowatts to kilojoules per second:

N = 16.8 kW = 16.8 kJ/s

Now, we can calculate the energy generated:

Energy = N × τ = 16.8 kJ/s × 20 s = 336 kJ

Therefore, the energy generated by the heater is 336 kilojoules (rounded to the nearest whole number).

Summary of Results

- The volume of water heated is approximately 2 liters. - The energy generated by the heater is approximately 336 kilojoules. - The mass of water heated is approximately 2 kilograms.

Please note that these calculations assume no energy losses during the heating process and that the specific heat capacity and density of water remain constant.