Answers. 1. The relativistic mass is the rest mass / sqrt(1 - (v/c)^2) which in this case is 223.607356769625 kg. The kinetic energy is the change in mass, so

Answers. 1. The relativistic mass is the rest mass / sqrt(1 - (v/c)^2) which in this case is 223.607356769625 kg. The kinetic energy is the change in mass, so 222.607356769625 kg which through the conversion E = mc^2 is about 2 * 10^19 Joules. The momentum is mass times velocity which is about 6.7 * 10^10. 2. No. You'd be jettisoning a very nasty rock. That will immediately explode on impact. 3. There is no limit to the mass it could have. 4. The first thing it hit, would convert into highly energized particles still moving in the same direction, which would hit new particles and so on. The result of the cascade will be to generate a shower of high energy particles with the same energy and momentum as the original. Or in short, BOOM! 5. Because of conservation of energy/mass, no. Even with 100% efficiency, the reactor would have to lose the same amount of mass that shows up as kinetic energy in the ejected particle.