Unit Four – Force Interaction Model PRS - Forces 10/25/06 © Copyright 2014 – all rights reserved www.cpalms.org
© Copyright 2014 – all rights reserved www.cpalms.org A force is: an interaction between two objects that can be described as a push or a pull. © Copyright 2014 – all rights reserved www.cpalms.org
The FORCE DIAGRAM is used to show forces acting on a particle. A particle is used to represent an object. All of the mass is assumed to be concentrated at a single point and the entire object is assumed to be doing the same thing. The reason we use particle models is to simplify things. A free body diagram is used to represent forces on an extended body. © Copyright 2014 – all rights reserved www.cpalms.org
To draw a force diagram: 1) Draw a picture of the situation © Copyright 2014 – all rights reserved www.cpalms.org
To draw a force diagram: 2) Identify all force interactions. A SYSTEM SCHEMA will help organize the interactions. hand ball air earth © Copyright 2014 – all rights reserved www.cpalms.org
To draw a force diagram: 3) Represent the object with a dot (a particle). © Copyright 2014 – all rights reserved www.cpalms.org
To draw a force diagram: 4) Draw an arrow to represent each force interaction involving the object. Arrows should be drawn out from the dot, in the direction the object experiences the force. © Copyright 2014 – all rights reserved www.cpalms.org
To draw a force diagram: 5) Label each arrow with object, object notation. Fhand, ball Fearth, ball © Copyright 2014 – all rights reserved www.cpalms.org