A 0.21-kg coffee mug is made from a material that has a specific heat capacity of 960 J/(kg·C°) and contains 0.23 kg of water. The cup and water are at 25°C. To make a cup of coffee, a small electric heater is immersed in the water and brings it to a boil in two minutes. Assume that the cup and water always have the same temperature and determine the minimum power rating of this heater.