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**kenan** If an electron and it positron (antielectron), each with a rest mass of 9.11 x 10^-31 kg, met and annihilated each other, how much radiant energy would be produced? (In such a reaction involving matter and antimatter, the mass is completely converted into energy in the form of gamma rays.) Assume that the particles were barely moving before the reaction.

Answer:1.64 x 10^-13 J

The Sun radiates away energy at a rate of 3.9 x 10^26 W. At what rate is it losing mass due to this radiation?

Answer: 4.3 x 10^9 kg/s