Airplane A , starting from rest with constant acceleration, requires a runway 600{\rm m} long to become airborne. Airplane B requires a takeoff speed twice as great as that of airplane A , but has the same acceleration, and both planes start from rest. A.) How long must the runway be for airplane B? B.) If airplane A takes time T to travel the length of its runway, how long (in terms of T ) will airplane B take to travel the length of its runway?