A person is pushing a box across a table. The measured forces on the box are 10N, 14N, -7N, -10N.Which force is represented by -7N?

The positive forces are the upward and downward forces that balance: the normal force and gravity. The horizontal push is 14 N, while the force opposing the motion is negative, so −7 N represents the force of friction.

AI-written and checked against the verified answer.