spring problem (with velocity)?

Question

A 30.0 g object is attached to a horizontal spring with a force constant of 5.0 N/m and released from rest with an amplitude of 25.0 cm. What is the velocity of the object when it is halfway to the equilibrium position if the surface is frictionless?

Answer 1

use work-energy theorem...conserve K.E.of object + P.E. of spring....

Answer 2

1/2k x^2 = 1/2mv^2
so
v = sqrt(k/m)*x

v = 3.23 m/s