Hi to all. What seemingly was originally thought as an extremely easy question was not well understood. So it's written very specifically..
It is meant to be understood that a [URL="https://en.wikipedia.org/wiki/Capacitor"]capacitor[/URL] starts with 0J and 0V in it. Next the switch is closed in order to connect the battery to the capacitor in order to charge it up to the exact same voltage level of that of the battery.
There is now 7.2 milliJoules of energy stored in the capacitor.

I am only referring to the schematic presented, which works exactly like what...