A wooden plank is raised at one end to make an angle of 30° to horizontal. A 2.0 kg box is placed on the incline 1.0 m from the lower end and is given a small push to start it moving (just to overcome static friction; ignore the acceleration of this push). The coefficient of friction between box and plank is 0.20. Determine
(a) rate of acceleration down the incline and
(b) speed of the box at the bottom. (Assume initial speed of the box is zero).