A $5-m-$ -long ladder has a mass of $15 \mathrm{kg}$ and is placed against a house at an angle $\theta=20^{\circ} .$ Knowing that the ladder is released from rest, determine the angular velocity of the ladder and the velocity of end $A$ when $\theta=45^{\circ}$ Assume the ladder can slide freely on the horizontal ground and on the vertical wall.