Question: 1 kg mass has energy in joules?
Answer: This implies, for instance, that 1 kilogram of matter is equivalent to an energy E = (1 kg)×(3×108 m/sec)2 = 9×1016 kg m2/sec2. An energy of 1 kg m2/sec2 is known as 1 joule, for short. The joule is not a unit of energy that is used much in everyday life.