A ball of mass 200 g rests on a vertical post of height 20 m . A bullet of mass 10 g , travelling in horizontal direction, hits the centre of the ball. After collision both travels independently. The ball hits the ground at a distance 30 m and the bullet at a distance of 120 m from the foot of the post. The value of initial velocity of the bullet will be (if $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2$ ):
