Physics Mechanics
posted by D .
Particle A and particle B are held together with a compressed spring between them. When they are released, the spring pushes them apart, and they then fly off in opposite directions, free of the spring. The mass of A is 3.00 times the mass of B, and the energy stored in the spring was 132 J. Assume that the spring has negligible mass and that all its stored energy is transferred to the particles. Once that transfer is complete, what are the kinetic energies of each particle A and B in Joules?

first conservation of momentum
MassA*Va+Massb*Vb=0
3Va+Vb=0
Vb=3Va
then energy:
132=1/2 MassA*Va^2+1/2 MassB*Vb^2
264=massB (3Va^2+Vb^2) or
264=MassB (3Vb^2/9+Vb^2)) or
264=4/3 MassB*Vb^2
so you know then that KE massb is
KEmassB=132*3/4 so the remaining 1/4 must be KEmassA
check my work 
Thanks a lot. Your answer are both right. Thank you so very much.