Physics education research, electronic materials, and the musings of Christopher Moore, Ph.D.

This is another question I have been having quite some trouble with. I do know the answer is 3.1 m/s, and I have tried many formulas and paths to try to get to this answer. I believe it has something to do with the formula F=kx but I am not sure.

a toy company hires you to construct a device that uses a small spring to launch 15g foam pellets. The spring requires an average force of 5.70 N to compress it 1.30 cm. Determine the speed of one of the foam pellets as it leaves the spring

Thanks