Laplace Transforms · Medium problem

A $2$-kg mass on a spring with $y''+4y=0$ starts at $y(0)=0$ but is given an initial momentum of $6\text{ kg}\cdot\text{m/s}$ (so $y'(0)=$ momentum$/$mass). Use the Laplace transform to find $y\!\left(\dfrac{\pi}{4}\right)$.