My attempt:
Relative velocity, v = s/t = 20/0.02 = 1000 m/s
Velocity of each bullet, u=v/2 =500 m/s
Now we have to find loss in energy,
We know, Q=mcΔT =(20/1000)(500)(50) = 500 J per bullet
Total energy loss= 2(500) = 1000 J
Now, I know that in the next step, we have to somehow correlate...