Each of the two rods shown is of length $L=1 \mathrm{m}$ and has a mass of $5 \mathrm{kg}$. Point $D$ is connected to a spring of constant $k=20 \mathrm{N} / \mathrm{m}$ and is constrained to move along a vertical slot. Knowing that the system is released from rest when rod $B D$ is horizontal and the spring connected to point $D$ is initially unstretched, determine the velocity of point $D$ when it is directly to the right of point $A$