Velocity Of An Object Accelerated By A Spring

[fcv33]

Homework Statement

I'm pulling my hair out over this problem. A spring with a force constant of k is compressed x meters. An object of mass m is placed against the spring. The spring is then released. At what velocity is the object moving at the instant that is ceases to touch the spring?

Homework Equations

E=0.5kx^2

The Attempt at a Solution

I'm really unsure. All of my solutions don't seem realistic.

 

[morbidwork]

Using Energy:
E=0.5kx^2=Kinetic Energy=0.5mv^2.

solve for v=((k/m)^1/2)*x
where x is initial displacement of spring.

Using F
F=-kx x is negative therefore
F=kx=ma

a=dv/dx*dx/dt = dv/dx*v
vdv=(kxdx)/m integrate
0.5v^2=0.5k/m x^2
v=((k/m)^1/2)*x