Marc attaches a falling 500-kg object with a rope through a pulley to a paddle wheel shaft. He places the system in a well-insulated tank holding 25 kg of water. When the object falls, it causes the paddle wheel to rotate and churn the water. If the object falls a vertical distance of 100 m at a constant speed, what is the temperature change of the water? (1 kcal = 4,186 J, the specific heat of water is 4,186 J/kg·°C, and g = 9.8 m/s²)