The electric kettle has a power consumption of 1.25 kW. How long will it take for 1.5 liters of water to boil

The electric kettle has a power consumption of 1.25 kW. How long will it take for 1.5 liters of water to boil out of a boiled kettle with the lid open? The efficiency of the electric kettle should be taken equal to 92%

The power of the kettle is given P = 1.25 kW. K = 92% efficiency of the electric kettle. The amount of boiled water V = 1.5 liters. Q = 2260 kJ / kg specific heat of vaporization of water.

Find the time during which 1.5 liters of water will boil out of the kettle.

To solve this problem, you need to divide the total amount of heat required for the evaporation of water by the power of the kettle, taking into account its efficiency. The mass of water is M = 1.5 kg, since its density is 1000 kg / m3.

t = Q * M / (P * K) = 2260 kJ / kg * 1.5 kg / (1.25 kW * 0.92) = 3390 / 1.15 = 2947 sec.