Boxes A and B are connected to each end of a light vertical rope, as shown in the following figure. A constant upward force 84.0 N is applied to box A. Starting from rest, box B descends 12.5 m in 4.50 s. The tension in the rope connecting the two boxes is 34.0 N (Figure 1). Figure r Part A What is the mass of box B? Express your answer with the appropriate units. mB= Value A F B ? Units Submit Previous Answers Request Answer X Incorrect; Try Again; 2 attempts remaining Part B What is the mass of box A? Express your answer with the appropriate units. ? A mA = Value Units Submit Request Answer < 1 of 1 >