Explosion Physics Problem: Solving for Velocity and Direction of Third Piece

[silverwing57]

Hey guys, just wanted to ask for help on this problem I'm having with this assignment. The questions is a ball explodes into three pieces. Two pieces of equal mass fly off to the south and west, perpendicular to each other at 20m/s. The third piece has twice the mass as the other two (same if they were combined). What is the speed and direction of the third piece?

So far I have come to an answer which I am pretty sure is wrong. I thought, using kinetic energy, that an equal amount of energy would be given to the big half and the two little quarters as they are evenly divided. Therefore, since the energy of the big half is the same as the two quarters, and the weight is the same, that the velocity would be the same too? I would really appreciate any help on this one. Thanks again.

 

[enricfemi]

why not consider the momentum.

the kinetic energy should not work because it produced energy from inside

 

[chaoseverlasting]

The net linear momentum is conserved, and momentum is a vector property.

 

[silverwing57]

ah, I see, I didn't think to consider momentum, thanks heaps guys.