1. Weight of the box (W): This force acts vertically downward due to gravity.

2. Normal force (N): The wall exerts a normal force on the box perpendicular to the wall, preventing it from moving into the wall.

3. Applied force (F): The person is pushing the box upward at a 28-degree angle above the horizontal.

To keep the box in equilibrium, the sum of forces in both the horizontal and vertical directions must be zero.

Horizontal Direction:

$$\sum F_x=0$$

$$F\cos28^\circ - N_x=0$$

$$N_x=F\cos28^\circ$$

Vertical Direction:

$$\sum F_y=0$$

$$F\sin28^\circ + N_y - W=0$$

$$N_y=W-F\sin28^\circ$$

Since the normal force is the reaction force exerted by the wall, it must be positive. Therefore, from the equation for $$N_y$$, we can see that:

$$W > F\sin28^\circ$$

This means that the weight of the box must be greater than the component of the applied force in the vertical direction for the box to remain in equilibrium against the wall.

To summarize, the box remains in place against the wall when the applied force at a 28-degree angle is sufficient to overcome the frictional force and is less than the weight of the box.