A ball is projected from point A with velocity $20 \mathrm{~m} \mathrm{~s}^{-1}$ at an angle $60^{\circ}$ to the horizontal direction. At the highest point $\mathrm{B}$ of the path (as shown in figure), the velocity $\mathrm{v} \mathrm{m} \mathrm{s}^{-1}$ of the ball will be: