Verrrrry interesting question !
Force= (mass) x (acceleration)
(49.5kg) x (1.3 m/s²) =
Net force on the box is 64.25 newtons upward.
That's the net force. It's the combination of the tension in the rope
pulling the box up, and the force of gravity pulling the box down.
Force of gravity = "weight" = (mass) x (gravity) =
(49.5) x (9.8) = 485.1 newtons downward
The tension in the rope must be enough to balance the downward force
of gravity PLUS provide another 64.25 newtons upward.
Tension = (485.1) + (64.25) = 549.35 newtons