Well the first paragraph deals with what i mean about the Kinetic energy not the slug it's self
The kinetic energy is still there even after the slug is not (at least I think that's what you told me).
The last paragraph deals with the slug it's self which would pretty well vanish once it hit that shield no matter.
Now I have a question for you regarding the whole math, how do we KNOW what an object the size you described would do at C fractional speeds unless we've been able to propel an object C fractional and I just don't remember hearing about it lol.
Seriously though do scientists just "round up" from speeds we know about or do they pull it out of the air?
That's like the theory that if you press your hand against a table for a million years your hand and the table will merge, well considering neither your hand nor that table would possibly be there for a million years where did they get that from?
As far as energy loss goes assuming you get energy weapons I'm sure you'd know how to minimize energy loss (i.e focusing lenses and who knows what else) so assuming your hitting someone with 2 TW of power FOR 5 seconds (after whatever minimal energy loss you get) as opposed to hitting it with like 5 TW of power for about half a second.
Oh and I was trying to think of an analagy comparing the shield to the bullet with that brick wall bit not saying the shield is the literal equivilent of a brick wall because if you do that a marshmellow travelling at C fracionals would punch through it easily.
Their shields basically work in this sense (let me try to explain it as best I can) a split second energy burst wouldn't effect the overall stability of the shield, while a "drilling" sort of enery would.
My shields are actually inspired by the Langston fields form the Empire of Man series so I guess I could just flat out use the langston physics instead of trying to use my own lol
Langston fields worked where kinetic weapons were useless because the second it contacted the shield it slowed down so much that there was practically no kinetic force at all so they used fusion torpedoes and lasers a lot.
But they still had to open "ports" to launch torpedoes or fire missiles because the field worked both ways.