Suppose you warm up 520 grams of water (about half a liter, or about a pint) on a stove, and while this is happening, you also stir the water with a beater, doing 5×10⁴J of work on the water. After the large-scale motion of the water has dissipated away, the temperature of the water is observed to have risen from 21°C to 84°C.
What was the change in the thermal energy of the water?