An archer wants to test the speed of his shot (arrow) using limited sources. During the experiment, he hits a solid ball made up of clay soil having mass 0.4 kg kept at a height of 80 m on the lamppost of an apartment with his arrow. The arrow hits the centre of the ball with velocity v in a horizontal direction as illustrated below. After collision, both travel independently and it is found that the ball and the arrow fall on the ground at a distance of 25 m and 100 m, respectively from the lamppost. Determine the magnitude of v. (Consider the mass of the arrow to be 0.02 kg)