A wheel with rotational inertia I = 3 MR about its hori- zontal central axle is set spinning with initial angular speed wo. It is then lowered, and at the instant its edge touches the ground the speed of the axle (and CM) is zero. Initially the wheel slips when it touches the ground, but then begins to move forward and eventually rolls without slipping. (a) In what direction does friction act on the slipping wheel? (b) How long does the wheel slip before it begins to roll without slipping? (c) What is the wheel's final translational speed, UCM? [Hint: Use EF = ma, ETCM = ICMacM, and recall that only when there is rolling without slipping is UCM = WR.]