1. The problem statement, all variables and given/known data A point source in water provides 10 W of heat for 10 seconds, and is then shut off. The surrounding water has a temperature of 20 °C. Provide the temperature profile as a function of distance r and time t. 2. Relevant equations 3. The attempt at a solution If it were steady-state, I could use Gauss theorem to solve this problem. But since the point source is turned on and off again, I have no idea how to approach this problem. If someone could hint me in the right direction, it would be very much appreciated.