A thin uniform rod of length $\ell$ and mass $m$ is swinging freely about a horizontal axis passing through its end. Its maximum angular speed is $\omega$. Its centre of mass rises to a maximum height of\\
(1) $\frac { 1 } { 3 } \frac { \ell ^ { 2 } \omega ^ { 2 } } { g }$\\
(2) $\frac { 1 } { 6 } \frac { \ell \omega } { g }$\\
(3) $\frac { 1 } { 2 } \frac { \ell ^ { 2 } \omega ^ { 2 } } { g }$\\
(4) $\frac { 1 } { 6 } \frac { \ell ^ { 2 } \omega ^ { 2 } } { g }$