Use , of course. It should be very easy to solve .
The sun produces energy by effectively converting mass into energy via means of nuclear fusion reactions deep in its core. In one second the sun outputs roughly 3.86×1026 J of energy. How much mass does the sun lose in one second in order to produce this energy? [c=3×108 m/s]
[Specify units of 'kg', 'tons', or 'Mtons' in your answer, metric tons (=tonnes) only! Mtons = mega-tons, ktons = kilotons]