A cylindrical vessel containing a liquid is rotated about its axis so that the liquid rises at its sides as shown in the figure. The radius of vessel is 5 cm and the angular speed of rotation is $\omega$ rad s^{–1}. The difference in the height, h (in cm) of liquid at the centre of vessel and at the will be :

(1) $5\omega^2\over2g$

(2) $2\omega^2\over25g$

(3) $25\omega^2\over2g$

(4) $2\omega^2\over5g$