**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.

http://ift.tt/1qchvtt