To determine the amount of water in kilograms in the kettle, we can use the formula:
Energy = mass * specific heat capacity * temperature change
The energy consumed by the electric jug can be calculated using the power rating and the time taken:
Energy = power * time
Given: Power rating = 125 kW Time taken = 20 seconds
Energy = 125 kW * 20 s = 2500 kJ
The specific heat capacity of water is approximately 4.18 kJ/(kg·°C). The temperature change is the difference between the final boiling temperature (100 °C) and the initial room temperature (20 °C):
Temperature change = 100 °C - 20 °C = 80 °C
Now, we can rearrange the formula to solve for mass:
mass = energy / (specific heat capacity * temperature change)
mass = 2500 kJ / (4.18 kJ/(kg·°C) * 80 °C)
mass ≈ 75.30 kg
Therefore, approximately 75.30 kilograms of water are in the kettle.