An elevator and its contents have a combined mass of 6000 kg (Assume 4 significant digits). It is suspended by a single cable. (a) What force must the cable exert on the elevator when it is accelerating upward at 2.0 m/s?? (3 marks) (b) What force must the cable exert on the elevator when it is moving downward at a constant velocity of 2.0 m/s?