An electric kettle contain 1.5kg of water at 100 degree and powered by a 2.0kw electric element. He the thermostat of the kettle falls to operate, approximately how long will the kettle boil dry? (take the specific latent heat of vaporization of water as 2000kJkg
time=heatrequired/rate=1.5*Lv/20 and the time will be in seconds.
To determine how long the kettle will boil dry, we need to calculate the amount of energy required to vaporize the water and then divide it by the power of the electric element.
First, let's calculate the energy required to vaporize the water. The formula to calculate the energy is:
Energy = mass * specific latent heat of vaporization
Given that the mass of water is 1.5 kg and the specific latent heat of vaporization is 2000 kJ/kg, we can calculate the energy required:
Energy = 1.5 kg * 2000 kJ/kg
Energy = 3000 kJ
Next, we need to calculate the time it takes for the electric element to provide this amount of energy. The formula for calculating time is:
Time = Energy / Power
Given that the power of the electric element is 2.0 kW (convert to kJ/s),
Power = 2.0 kW * 1000 J/kW
Power = 2000 J/s
So, we can now calculate the time:
Time = 3000 kJ / 2000 J/s
Time = 1.5 s
Therefore, if the thermostat of the kettle fails to operate, it will take approximately 1.5 seconds for the kettle to boil dry.