Couldn't get the equation on here.

A stone, of mass m, is moving in a straight line along smooth horizontal ground. At time t, the stone has speed 1/. As the stone moves, it experiences a total resistance 3 force of magnitude Amvi , where A is a constant. No other horizontal force acts on the stone. 3 d _ (a) Show that (1: = ;lv2. (4) (b) The initial speed of the stone is 9 ms\". 36 Show that v (24-33102 . (7) (c) Find, in terms of A, the time taken for the speed of the stone to drop to 4 ms\". (3)