Boxes A and B are connected to each end of a light

Question

vertical rope. A constant upward force F = 80.0 N is
applied to box A. Starting from rest, box B descends 12.0 m in
4.00 s. The tension in the rope connecting the two boxes is 36.0 N.
What are the masses of (a) box B, (b) box A?

Answer 1

For A: 80-36-mg=ma
a = 2x/t^2
find a and solve for m
For B: mg - 36=ma
and a is the same (they're connected)

Answer 2

Ans. 4.34 kg; 5.3 kg

Answer 3

How to calculate acceleration