A mass resting on a frictionless horizontal surface is attached to one end of a spring. The other end of the spring is attached to a wall. It takes $4\mathrm{.}0$ J of work to compress the spring by $0\mathrm{.}15$ m$.$ If the spring is compressed$$and the mass is released from rest, it experiences a maximum acceleration of $11\mathrm{.}5$ m$/$s$2.$

Find the value of$$

$($a$)$ the spring constant

$($b$)$ the mass