Q10. An astronaut in a spaceship has a mass 75kg in the rest frame of the spaceship. The spaceship's length in its rest frame is 1150 m while its length as observed from the earth is 325 m The total energy of the astronaut in the earth's frame will be approximately: (a) 75 (c) 2.4x10 J (b) 750 J (d) 6.8x108 J