A $1\mathrm{.}40-$kg object is attached to a spring and placed on frictionless, horizontal surface. A horizontal force of $21\mathrm{.}0$ N is required to hold the object at rest when it is pulled $0\mathrm{.}200$ m from its equilibrium position $($the origin of the x axis$).$ The object is now released from rest from this stretched position, and it subsequently undergoes simple harmonic oscillations.

$($h$)$ Find the speed of the object when its position is equal to one$-$third of the maximum value.

$($i$)$ Find the magnitude of the acceleration of the object when its position is equal to one$-$third of the maximum value.