How long will 1.5 liters of water be heated from 20 to 100 ° C in an electric kettle with a capacity of 600 W

How long will 1.5 liters of water be heated from 20 to 100 ° C in an electric kettle with a capacity of 600 W, if its efficiency is 80%?

Initial data: V (volume of heated water) = 1.5 l = 1.5 * 10 ^ -3 m ^ 3; t0 (initial temperature) = 20 ºС; t (final heating temperature) = 100 ºС; N (kettle power) = 600 W; η (kettle efficiency) = 80% or 0.8.

Constants: ρ (water density) = 1000 kg / m ^ 3; C (specific heat of water) = 4200 J / (kg * K).

Kettle efficiency: η = C * m * (t – t0) / (N * t) = C * ρ * V * (t – t0) / (N * t).

t = C * ρ * V * (t – t0) / (η * N).

t = 4200 * 1000 * 1.5 * 10 ^ -3 * (100 – 20) / (0.8 * 600) = 1050 s or 17.5 min.