Water weighing 0.4 kg from 0 degrees to boiling with a power of 1000 W. Determine the efficiency of the kettle.

univerkov | March 23, 2021 | education

To find the efficiency of the indicated kettle, we use the formula: η = Npol / Nzatr = (Q / t) / Nh = Cw * m * Δt / (t * Nh).

Data: St. – beats. heat capacity of water (Sv = 4.2 * 10 ^ 3 J / (kg * K)); m is the mass of boiled water (m = 0.4 kg); Δt – temperature rise (Δt = 100 ºС); Nh – the power of the indicated kettle (Nh = 1000 W).

Let’s calculate: η = Cw * m * Δt / (t * Nh) = 4.2 * 10 ^ 3 * 0.4 * 100 / (t * 1000) = 168 / t.

Answer: The efficiency of this kettle is 168 / t.

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