Free Body Diagram

A free-body diagram is a graphical representation used to analyse
the forces exerted on objects by other objects. Below we show the
steps that you need to follow to draw the free-body diagram of a box that you push along a rough surface.
Follow the steps of the procedure in the order indicated.

1. Draw a sketch the situation described in the problem. (Figure 1)

2. Circle an object (objects) of interest in the sketch—we call this the system. (In this example is the box. Figure 2)

3. If the object in the system is somewhat smaller than the situation
being described or if all of its points move in the same way you can model the object as a point particle. Place at the side of the
sketch a "particle" dot to represent the system. (Figure 3)

4. Look for objects outside the system (external objects) that interact with the system.
Decide what objects are important and what objects are not. (In this example are the ground, the Earth and you).

5. Draw force arrows that represent the external interactions that affect the behavior of
the system object. Draw the tails of these force arrows beginning on the particle dot.
Draw the lengths of the arrows to represent the relative magnitudes of the forces. (Figure 4).

6. Label the forces in the diagram. Note: The forces in the diagram should represent the
force that some object outside the system exerts on the object inside the system. To start,
identify the external object that causes each force and also the object on which the force
is exerted (for example,FYouonBox, means the force that you exert on the box).

(Finish the figures, and the contact force + gravitational force)