A rod of length 50 cm is pivoted at one end. It is raised such that it makes an angle of $30^{\circ}$ from the horizontal as shown and released from rest. Its angular speed when it passes through the horizontal (in rad $\mathrm{s}^{-1}$ ) will be ( $\mathrm{g}=10 \mathrm{~ms}^{-2}$ )
