A ball rolls off the top of a staircase with a horizontal velocity u m/s. If the steps are h metre high and b metre wide, the ball will hit the edge of the nth step, if:

If the ball hits the nth step, then horizontal distance traversed = nh.Here, velocity along horizontal direction = u.Velocity along vertical direction = 0.∴ nb = ut-----------------(i)nh = 0 + 12gt2-----------(ii)From (i), t = nbv, ∴ = nh = 12g×(nbu)2n = 2hu2gb2