A Force is the cause of an acceleration, or the change in an object’s motion. The SI unit for force is a Newton (N). What role is force playing in each of these pictures?

A Contact Force is a force that arises from the physical contact of two object. Due to physical contact between two objects A Field Force is a force that can exist between objects, even in the absence of physical contact between the objects. Four basic Field Forces: Strong, Weak, Gravitational, Electric

Which of these is an example of a Field Force? Which of these is an example of a Contact Force?

A Force Diagram is a diagram of the objects involved in a situation and the forces exerted on the objects. Force Diagrams show force vectors as arrows with magnitude and direction

A Free-Body Diagram shows the forces on ONE object. A free-body diagram is used to analyze only the forces affecting the motion of a single object.

Steps to draw a free-body diagram: 1) Isolate and draw the object 2) Draw and label vector arrows representing all contact forces acting on the object. 3) Draw and label vector arrows representing all field forces acting on the object.

 Draw a free body diagram for the situation: A book is at rest on a tabletop.

 Draw a free body diagram from the situation: A rightward force is applied to a book in order to move it across a desk with a rightward acceleration. Consider frictional forces. Neglect air resistance