The projectile had horizontal velocity(which is constant till the time of explosion) =Originally Posted by Celia
I hope that you are familiar with the law of conservation of momentum(which is at the heart of Classical Mechanics).
Total momentum before explosion = Total momentum after explosion
(Let the mass of original projectile be m, then the mass of the fragments will be m/2 and m/2.)
Solving we get, .
I will continue from here(Do you know about maximum height and range?).