Spring compressed 25 cm with 5 kg mass: why is my speed wrong?

[alingy1]

Homework Statement

A vertical spring of negligible mass and spring constant k=1000N/m has a small object of mass M=5.0kg placed on its top. The spring is held compressed by distance of 25 cm from equilibrium position. The spring is released. Find speed of mass at equilibrium position.

Homework Equations

W spring=1/2kdeltax^2
W gravity=deltax*5*9.8
Total energy gain of mass=19J
Energy transferred into potential: 12.25J=mgh
Energy transferred into kinetic: 6.75J ---->v=1.64m/s

The Attempt at a Solution

The answer booklet says the answer is 2.76m/s!
Where did I go wrong?

 

[Chestermiller]

I don't know. The 19J seems too low. I got about 32 J. You didn't subtract the potential energy change twice, did you?

Chet

 

[NascentOxygen]

W spring=1/2kdeltax^2

When evaluating this, don't overlook that power of 2.