A horizontal spring of spring constant k and negligible mass is compressed through a distance y from its equilibrium length. An object of mass m that moves on a frictionless surface is placed at the end of the spring. The spring is released and returns to its equilibrium length.

What is the speed of the object just after it leaves the spring?

A.  \(y\sqrt {\frac{k}{m}} \)

B.  \(y\sqrt {\frac{m}{k}} \)

C.  \(y\frac{k}{m}\)

D.  \(y\frac{m}{k}\)

A