- A small ball of mass \(m\) is projected vertically upwards from a point \(O\) with speed \(U\). The ball is subject to air resistance of magnitude \(m k v\), where \(v\) is the speed of the ball and \(k\) is a positive constant.
Find, in terms of \(U , g\) and \(k\), the maximum height above \(O\) reached by the ball.