How Can I Calculate Kinetic Energy in an Explosion?

[shawtaroh]

Homework Statement

An explosion breaks an object into 2 pieces, one of which has 1.5 times the mass as the other. If the explosion released 7500J, how much kinetic energy did each piece acquire?

Homework Equations

conservation of momentum and energy

The Attempt at a Solution

I have tried using conservation of energy where the initial energy=7500J and no potential gravitational energy because i saw that that point of the explosion is y=0 and i said that Kinetic energy of object one plus kinetic energy of object 2=energy final right after the explosion.I just can't get anywhere

 

[Mindscrape]

You've done conservation of energy, but you ought to use momentum as well.