As respresented in the diagram below a constant 15-newton force, f is applied to a 2.5-kilogram box, accelerating the box to the right at 2.0 meters per second squared across a rough horizontal surfaceexplain the formulas and steps you use

#51, 52

Net force on the box is given by sum of all forces on the box

As per Newton's II law we can say

it is product of mass and acceleration of the object

given that

mass = 2.5 kg

acceleration = 2 m/s^2

here we know that

so we can say that

#53

Now we can say there are two forces acting on the box

1. applied force which is given as 15 N in forward direction

2. friction force on the box in opposite direction.

so friction force on this box will be 10 N