# Maximum speed in a spring-mass system

I am studying energy right now and I can use only gravitational potential energy, elastic energy and kinetic energy to solve some problems. My doubt is how can I prove that the maximum speed in a mass hanging on a spring is reached at the middle of the elongation of the spring.

The exercise shows the following situation: A block with mass $$m$$ is attached to an ideal spring (no mass) of an elastic constant $$k$$. The block is released when the spring is on his natural state. Consider no friction and that the system is conservative.

The question ask for the maximum speed of the block using energy only. I solved it already (with $$m=0.1$$ $$[kg]$$ and $$k=10\left[\frac{N}{m}\right ]$$ and assuming that the point $$0[m]$$ is when the spring reaches it maximum elongation and the block is released from a height of $$h\;[m])$$. Then, I got that the maximum speed is $$1[\frac{m}{s}]$$, but I assumed that the maximum speed is reached at the middle, so I want to know why this is true in these ideal conditions.