A star similar to our sun radiates energy at the prodigious rate of 4.8 x 10^26 W
(a) At what rate does this star convert mass into energy?
(b) Assuming that the star has radiated at this same rate for its entire lifetime of 4.8 x 10^9 y, and that its current mass is 1.7 x 10^30 kg, what percentage of its original mass has been converted to energy?