* Gravity: The box experiences a downward force of 35 N due to gravity.

* Your Upward Force: You apply an upward force of 39 N.

What's being applied?

You're applying a net upward force of 4 N. Here's how to calculate that:

* Net Force = Upward Force - Downward Force

* Net Force = 39 N - 35 N = 4 N

This net upward force is what overcomes gravity and lifts the box.