The kinetic energy formula is KE=12mv2KE = \frac{1}{2}mv^2KE=21mv2. Solve for vvv (v>0v > 0v>0).
v=2⋅KEmv = \sqrt{\frac{2 \cdot KE}{m}}v=m2⋅KE
v=2⋅KEmv = \frac{2 \cdot KE}{m}v=m2⋅KE
v=KE2mv = \sqrt{\frac{KE}{2m}}v=2mKE
v=KE2mv = \frac{KE}{2m}v=2mKE