Verticle Wave Problem

[timtng]

A load of mass .2 kg is hanging from a light spring whose elastic constant is 20 N/m. The load is pulled down .1 m from its equilibrium position and released.

How long is required for the load to reach its equilibrium position?

This is what I did:
T=2π(sqrt(m/k))=.628 s

my friend said the answer should be a fourth of that value, which is .157 s.

Is my friend correct?

Please help
Thanks

[yxgao]

Your friend is correct. The period you calculated is for one complete oscillation (that is, if the mass went pass equilibrium position, reached a stopping point, turned around, went pass equilibrium position again, and arrived at where you started from). From the stretched position, to get to equilibium requires 1/4 of a complete oscillation.