A $1.3-\mathrm{kg}$ block is pushed up against a stationary spring, compressing it a distance of $4.2 \mathrm{~cm}$. When the block is released, the spring pushes it away across a frictionless, horizontal surface. What is the speed of the block, given that the spring constant of the spring is $1400 \mathrm{~N} / \mathrm{m}$ ?