
The ball needs to just cross 4 steps to just hit 5th step
Therefore, horizontal range
R==4×0.1m0.4m
The formula to calculate the horizontal range is given by
R=ut...(1)
Similarly, the vertical height covered by the ball is given by
h=21gt2...(2)
From equations (1) and (2), it follows that
4×0.1=21gt2⇒0.4=21g(u0.4)2⇒u2=2⇒u=2ms−1
Therefore, x=2.