Ok, so let's say I have a weapon that can fire a 2 centimeter diameter rod that is 25 centimeter long at a speed of 1/3 the speed of light, or 100,000,000 meter seconds with a weight of 5kg. I estimate the energy at 2.5 e16 joules, or approximately 6 megatons. Now, my question is complicated, I figure a large part of that energy will be heat as it starts to touch the atmosphere at the barrel's mouth as it exit the weapon. How do I go about calculating how much energy would probably be wasted burning up in the atmosphere on the surface of the earth if I shoot the weapon to the horizon, so say going through roughly 100km of dense atmosphere at normal sea level. Next how far do you think such a rod would travel down to the center of the earth? Next loud would this potentially be? from this site http://www.makeitlouder.com/Decibel Level Chart.txt I'd estimate between 275 decibel or so. finally, the air molecule it hits as it exit the weapon, would the rod cause a shower of mainly x-ray? Or is it possible that it would create mainly gamma ray as it travels and interacts with matter? thank you very much for your answers.